UNITED STATES OF AMERICA
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FOOD AND DRUG ADMINISTRATION
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CENTER FOR BIOLOGICS EVALUATION AND RESEARCH
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VACCINES AND RELATED BIOLOGICAL PRODUCTS
ADVISORY COMMITTEE
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97th MEETING
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THURSDAY,
FEBRUARY 19, 2004
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The
Advisory Committee met at 8:30 a.m., in the Embassy Rooms of the Four Points
Sheraton, 8400 Wisconsin Avenue, Bethesda, Maryland, Dr. Gary Overturf,
Chairman, presiding.
This transcript has not been edited or corrected, but appears as received from the commercial transcribing service. Accordingly the Food & Drug Administration makes no representation as to its accuracy.
PRESENT:
GARY D. OVERTURF, M.D., Chairman
NANCY J. COX, Ph.D., Consultant
MICHAEL D. DECKER, M.D., Industry Representative
WALTER DOWDLE, Ph.D., Consultant
THEODORE EICKHOFF, M.D., Consultant
MONICA M. FARLEY, M.D., Member
BRUCE GELLIN, M.D., M.P.H., Consultant
JUDY D. GOLDBERG, Sc.D., Consultant
RUTH A. KARRON, Member
PHILIP S. LaRUSSA, Ph.D., Member
DAVID MARKOVITZ, M.D., Member
PAMELA McINNES, D.D.S., Consultant
ARNOLD S. MONTO, M.D., Consultant
MARTIN MYERS, M.D., Consultant
PRESENT: (cont'd)
PETER PALESE, Ph.D., Member
STEPHEN C. PHILLIPS, D.O., M.P.H., LTC(P) USMC,
Member
CINDY LYN PROVINCE, R.N., M.S.N., Consumer
Representative
WALTER ROYAL, III, M.D., Member
BONNIE M. WORD, M.D., Member
WILLIAM FREAS, Ph.D., Acting Executive Secretary
PRESENTERS:
PHIL MINOR, M.D.
FDA REPRESENTATIVES:
WILLIAM EGAN, M.D.
ROLAND A. LEVANDOWSKI, M.D.
ZHIPING YE, M.D., Ph.D.
A-G-E-N-D-A
PAGE
I. Call
to Order and Announcements 4
II. Strain
Selection for Influenza Virus
Vaccine
for the 2004-2005 Season
A. Options for Strain Selection 6
B. Committee Discussion and 15
Recommendations
C. Use of Mammalian Tissue Culture
for Reference Strain Isolation
‑‑ FDA Perspective 68
‑‑ NIBSC Perspective 102
III. Adjourn 151
P-R-O-C-E-E-D-I-N-G-S
(8:37
a.m.)
DR.
FREAS: Good morning. Before we officially start the meeting, I
would like to go around and introduce to the members of the public those
committee members that are seated at the head table.
Starting
on the right-hand side of the room, we have Dr. David Markovitz, Professor,
Division of Infectious Diseases, University of Michigan Medical Center. Sitting next to him is Dr. Walter Dowdle,
Senior Public Health Consultant, The Task Force for Child Survival and
Development. Next we have Dr. Judith
Goldberg, Director, Division of Biostatistics, New York University School of
Medicine.
Next
we have Dr. Ruth Karron, Associate Professor, Johns Hopkins University School
of Hygiene and Public Health. Next we
have Dr. Walter Royal, Associate Professor of Medicine, Morehouse School of
Medicine. Next we have Dr. Monica
Farley, Professor of Medicine, Emory University School of Medicine.
Next
we have Pamela McInnes, Deputy Director, Division of Microbiology and
Infectious Diseases, NIH. Next we have
Ms. Cindy Lyn Province, Associate Director, Bioethics Center of St. Louis. Next we have Dr. Bruce Gellin, Director,
National Vaccine Program.
Next
we have ‑‑ joining with us this morning Dr. Stephen Phillips,
Director, Deployment Medicine and Surveillance, Office of the Assistant
Secretary of Defense. Next, to the
Chairman of this committee, Dr. Gary Overturf, Professor, Pediatrics and
Pathology, University of New Mexico School of Medicine.
Next
we have Dr. Philip LaRussa, Professor of Clinical Pediatrics, Columbia
Presbyterian Hospital. Next we have Dr.
Martin Myers, Co-Director, Public Health Policy and Education, Sealy Center for
Vaccine Development, University of Texas Medical Branch. Next we have Dr. Bonnie Word, Assistant
Professor of Pediatrics, Baylor College of Medicine, Texas Children's Hospital.
Next
we have Dr. Peter Palese, Chairman and Professor, Department of Microbiology,
Mount Sinai School of Medicine. Next we
have Dr. Arnold Monto, Professor at the University of Michigan. Next we have Dr. Ted Eickhoff, Professor of
Medicine, University of Colorado Health Sciences Center.
Next
is our non-voting industry representative, Dr. Michael Decker, Vice President,
Scientific and Medical Affairs, Aventis Pasteur. Next we have Dr. Nancy Cox, Chief, Influenza Branch, Center for
Disease Control and Prevention. And at
the end of the table we have Dr. Reverend Levandowski ‑‑ Dr. Roland
Levandowski ‑‑ excuse me ‑‑
(Laughter.)
‑‑
okay, from FDA.
I
would like to welcome all of you here.
CHAIRMAN
OVERTURF: I'd like to call the ‑‑
I'd like to welcome you back for the second day of this VRBPAC meeting.
At
this time, we have an opportunity for an open public hearing, and I request
that anybody who would like to make a statement to please make their way to a
microphone. Please announce who you are
and any groups that you may represent.
Okay. Since we have nobody who is approaching the
microphone, I assume that there is nobody wanting to address the committee
during the open public hearing. So we
will proceed to the questions for this committee meeting, and that is the
options for the strain selection for the 2004-2005 influenza vaccine, and I'll
turn the meeting over to Dr. Levandowski.
DR.
LEVANDOWSKI: Okay. Thank you.
Good
morning, everybody. I'll just plunge
right into this, and actually this should say options for Influenza A H1N1 and
H1N2, or just Influenza A H1.
Just
to summarize, I'll try to summarize information from yesterday as a reminder of
what we were looking at for each of the strains, and then go through options
that are possible for strain selection.
The
H1N1 and H1N2 viruses ‑‑ of course there have been relatively few
of these viruses isolated during this season.
The isolates have come mainly from sporadic cases that have been in the
Americas, Asia, and Europe, but there have been some outbreaks. I don't know if we emphasized that. There have been outbreaks of Influenza A
H1N1 and H1N2 in Iceland and the Ukraine during this past season.
The
HA on most of the H1 strains antigenically are similar to the current vaccine
strain, which is A/New Caledonia/20/99, and the H1 virus is generally seen to
be well inhibited by antisera from people who have been immunized with the
current vaccines that contain A/New Caledonia/20/99.
In
addition to that, we have high growth reassortants for A/New Caledonia/20/99
that are available or used in current manufacturing, and all of that is very
well worked out at this time. So the
first option for this ‑‑ for the H1 strain is to retain the New
Caledonia/20/99 virus.
And
in favor of that, as I mentioned, most of the recent H1 viruses are
antigenically very close in nature to the hemagglutinins. They're very close in nature antigenically
to the A/New Caledonia vaccine strain.
The
current vaccines, of course, appear to be well matched to the HA of the current
strains, and the manufacturing has worked out and the yield is very
predictable. I'm not in favor of
that. The con here is that there have
been relatively few strains to look at for analysis.
The
second option for this, of course, is to change to use a more recent H1N1
virus, and in favor of that there is the possibility that a more recent strain
might provide a closer match with hemagglutinins and the neuraminidases of the
contemporary strains.
But
against that the new strain is not likely to be superior in terms of
immunogenicity or efficacy compared to the current vaccine strain, and there
aren't ‑‑ the manufacturing issues have not really been worked out
for any strains at this point.
And
the third option, of course, always is to defer the recommendation. In favor of that might be that there could
be analysis of more contemporary strains if those were identified, and maybe
that would make a closer match for the hemagglutinin and neuraminidase of next
year's vaccine. But against that is the
fact that it appears that there will be little new information that's
forthcoming, since there are so few H1N1 viruses that are causing disease.
So
moving on for the H3N2 viruses, by way of review, of course everyone knows that
the Influenza A H3N2 viruses have predominated globally since September of
2003. The HA on most of these strains
are antigenically distinguishable from the current vaccine strain, which is
A/Panama/2007/99, and they are more closely related to the A/Fujian/411/2002
strains.
At
this point, the influenza season appears to be declining in the northern
hemisphere, and, of course, we also know that the majority of the strains that
are ‑‑ that have been isolated are not that well inhibited by
antisera produced against the current vaccines in people.
There
are ‑‑ at this point, there are high growth reassortants of the ‑‑
of A/Fujian/411/2002-like strains, and that includes, as we heard yesterday,
reassortants for A/Wyoming/3/2003 and A/Kumamoto/102/2002. And we know that those grow reasonably well.
So
for H3N2, again, the first option would be to retain the A/Panama strain as the
vaccine strain. And in favor of that,
of course, the manufacturing is very well worked out, and it's very highly
predictable. But against that we know
that the HA of most of the H3N2 viruses are antigenically distinguishable from
the current vaccine strain. And
serological tests with current vaccines indicate that the majority of strains
are not very well inhibited by antiserum from people who are immunized with the
Panama strain.
And
also, as we know, the H3N2 influenza viruses are often responsible for
significant morbidity and mortality, and I think that was highlighted in Maria
Zambon's talk.
So
the second option for H3N2 is to choose a more recent H3N2 virus, and in favor
of that a more recent strain could provide a closer match with the
hemagglutinin and neuraminidase of contemporary strains. There are high growth reassortants for
Fujian/411-like viruses available for manufacturing, and they appear to be
reasonable in terms of their yield.
And, again, reason to do this is because H3N2 viruses are often
responsible for more significant morbidity and mortality.
Against
this we don't really know that a new strain would actually provide superior
immunogenicity or efficacy compared to the current vaccine strain, and we
wouldn't know that until the vaccine was actually made and used.
The
third option, of course, would be to defer the recommendation. In favor of that it might give us time to
look at some other strains, and a different, more recent strain might provide a
closer match with other contemporary H3N2 viruses in terms of the hemagglutinin
and neuraminidase.
And,
again, because the H3N2 viruses are associated with significant morbidity and
mortality, that might be something to consider. Against that there is already a lot of information about how the
H3N2 viruses have evolved during this current season, and it seems very
unlikely that we're going to get any additional information in the next few
weeks that would really add to what we already know about the current ‑‑
the majority of the current strains.
And we don't really know whether another strain would be superior in
terms of efficacy for vaccine production.
So
for Influenza B ‑‑ again, to summarize ‑‑ the Influenza
B viruses that have been circulating are in both of the known HA ‑‑
two known HA lineages. Strains that are
in the vaccine HA lineage ‑‑ that is, the Victoria/287-like viruses
‑‑ seem to be antigenically very similar to the current vaccine
strain, which is B/Hong Kong/330/2001-like virus.
Strains
in the other HA lineage ‑‑ that is, the B/Yamagata/16/88 lineage,
however, are the predominant viruses, and those have been represented by the
reference strain B/Shanghai/361/2002.
Even
though the Influenza B viruses have not been the predominant viruses in the
recent months, strains similar to the B/Shanghai/361 virus have been isolated
in many parts of the world. So they're
out there circulating widely.
And
although this B/Shanghai/361/2002 virus is related to previous vaccine strains,
that and similar viruses are antigenically distinguishable from the previous
B/Yamagata HA lineage viruses that were used in vaccines.
There
is a little bit of evidence that the Influenza B viruses that are similar to
B/Shanghai/361 are less well inhibited by antisera from people who have been
immunized with vaccines that contained the virus in the same lineage, but even
more so it's very apparent that the current vaccines do not inhibit these newer
viruses as well.
And
it's particularly obvious in looking at antisera from children where there's a
true dichotomy, where there's a pretty reasonable vaccine response to the
vaccine strain, but really no cross-reactive antibodies against the other HA
lineage.
And
we also have heard that there are some ‑‑ there are a number of
candidate viruses in the B/Shanghai/361/2002 category that are available for
potential vaccine use. But we don't
really have a lot of information about those at this point, because they've
only just recently been distributed to ‑‑ some of them have been
recently distributed to manufacturers for evaluation.
So
we don't really know exactly what their growth characteristics are going to be,
although we heard from Greg Slusaw that the B/Jilin strain at least seemed to
be a moderate strain in terms of its growth on early ‑‑ very early
examination.
So
the options for Influenza B ‑‑ one, we could retain the B/Hong
Kong/330/2001-like virus, which is the current vaccine strain. For that manufacturing is very well defined,
and it's very predictable. Against that
at the moment the predominant strains are not in the same HA lineage, and those
strains have been found in many parts of the world at this point.
Also
against that, Influenza B viruses that are not in the vaccine HA lineage are
not that well inhibited by post-infection and post-immunization antisera. And in particular, as I mentioned, the
immunologically naive young children ‑‑ sera from immunologically
naive young children who get the current vaccine don't seem to inhibit the
B/Yamagata lineage viruses at all.
So
the second option is to use a more recent Influenza B virus, and in favor of
that the vaccines might provide better coverage for the currently circulating
Influenza B viruses. There are several
candidate strains that have been identified, and those are being examined right
now.
Against
that a new strain, you know, might not provide superior immunogenicity, and use
of a new Influenza B strain could cause some difficulties in manufacturing,
since we don't really have a lot of information at this point.
And
then, finally, the third option, of course, is to defer the
recommendation. And in favor of that
that would provide more time to evaluate these candidate vaccine strains, and
that might permit us to find the best match for a strain that matches the
contemporary hemagglutinin and neuraminidases.
Against that we don't really know whether a new strain really would be ‑‑
how much better that would be in terms of its actual use.
And
so I'll stop there, and just remind the committee that the question is, of
course, what strains should be recommended for the antigenic composition of the
2004-2005 influenza virus vaccine that we'll be using in the United States?
And
the answer to this question should, of course, be based on the epidemiology and
antigenic characteristics of the viruses, serologic responses, and availability
of candidate strains for use. And I can
answer a few questions, if there are ‑‑ if you want me to.
CHAIRMAN
OVERTURF: Are there any questions for
Dr. Levandowski? Yes.
DR.
FARLEY: This is on the same track as
yesterday's questions about B virus.
This is for H1 virus, Influenza A H1.
The numbers that we had in the handout were very, very small, as you've
referred to. I think we only had 10
that showed the responsiveness to the previous vaccine sera.
If
we look at the other WHO sites, does that give us reassurance that everything ‑‑
the additional numbers that that might bring in were also responsive?
DR.
LEVANDOWSKI: Maybe Nancy can ‑‑
DR.
FARLEY: Sort of a question for Nancy.
DR.
LEVANDOWSKI: Maybe Nancy Cox would like
to answer that.
DR.
COX: Sure. This is Nancy Cox. The
only significant outbreaks that have occurred since October have been in the
Ukraine and Iceland. Those ‑‑
isolates from those outbreaks were analyzed by the WHO Collaborating Center in
London, and the antigenic characteristics of those viruses were very similar or
identical to the antigenic characteristics of the viruses that we've displayed
in our table.
So
I think that although the numbers are really small, if you look back at the
previous time interval, which was during the southern hemisphere influenza
season, that data also is reassuring that, you know, what we have ‑‑
we've looked at what is available, and it is very consistent data that we're
seeing from all centers with small numbers of viruses, and the viruses are very
well inhibited by antiserum to the New Caledonia vaccine strain.
CHAIRMAN
OVERTURF: Are there other questions for
Dr. Levandowski?
At
this time, I think I should open up the discussion. And what I would prefer to do is to have a discussion regarding
each selected strain, and we'll open it up with the H1N1 strain. And then after that we can vote on that
strain and the recommendations, and then that will be followed by a discussion
by each strain in sequence.
Is
there any discussion regarding H1N ‑‑ further discussion about H1N1
strains? Any comments?
Well,
the options ‑‑ the options for the H1N1 strain is to either retain
the current New Caledonian strain or to go to a more recent strain or to defer
the recommendation. And so those are
your three options when we polled the committee on a vote.
And
so I will start with David and have you go around the table and all state your
vote.
DR.
MARKOVITZ: Yes. David Markovitz. I would like to indeed vote to retain the current New Caledonia
strain. Strains like the current
circulating viruses are all very similar to this, and it's up and running and
in production, and so it seems fairly clear that that's the way we should go.
DR.
DOWDLE: Walter Dowdle. And I would vote to retain the current
Caledonian strain.
DR.
GOLDBERG: Judith Goldberg. I vote to retain it.
DR.
KARRON: Ruth Karron. I'd vote to retain the A/New Caledonia
strain.
DR.
ROYAL: Walter Royal. I vote to retain the A/Caledonia strain.
DR.
FARLEY: Monica Farley. I vote to retain it.
DR.
McINNES: Pamela McInnes. I vote to retain the A/New
Caledonia/20/99-like virus in the current vaccine.
MS.
PROVINCE: Cindy Province. I vote to retain the current strain.
DR.
GELLIN: Bruce Gellin. I also vote to retain the current New
Caledonia strain.
DR.
PHILLIPS: Steve Phillips. On behalf of Department of Defense, I vote
to retain.
CHAIRMAN
OVERTURF: This is Gary Overturf. I also would retain the current New
Caledonia strain.
DR.
LaRUSSA: Phil LaRussa. I vote to retain.
DR.
MYERS: Martin Myers. Retain.
DR.
WORD: Bonnie Word. Vote to retain.
DR.
PALESE: Peter Palese. Retain, please.
DR.
MONTO: Arnold Monto. Retain.
DR.
EICKHOFF: Ted Eickhoff. I think there's an echo in this room.
(Laughter.)
Vote
to retain. This is the easy one.
CHAIRMAN
OVERTURF: Nobody wanted to buck a
trend.
DR.
FREAS: Just for the record, I'd like to
announce that we're at the end of the voting members of the table, but we do
ask industry for their opinion.
DR.
DECKER: The industry applauds the
wisdom of the committee.
(Laughter.)
CHAIRMAN
OVERTURF: Is there any further
comment? I think there's a unanimous
vote to retain the New Caledonian strain for the H1N1 Influenza A.
The
second issue is regarding the H3N2 strain, and I'll open this issue up to
discussion again. And, again, there are
three alternatives for that. One is, of
course, to ‑‑ to use a more recent influenza A/Fujian strain or to
retain the A/Panama strain or to defer this decision as well.
So
I think those are the three options that we'll be voting on, and I'll open this
up for discussion at this point. Is
there any discussion?
Yes,
Martin.
DR.
MYERS: I guess it's a ‑‑
like on the last one, I have a question for Nancy. Some of the recent isolates were ‑‑ that you showed
yesterday in your table were less reactive against the Fujian. Is there further drift that you anticipate
occurring?
DR.
COX: We have looked very carefully at
recent viruses, and we really concentrated on looking at viruses that are in
slight ‑‑ those slightly different genetic groups that have the
changes at 126 in one group, or the change ‑‑ and the changes at
197 ‑‑ sorry, 193 and 227 in the other group.
And
we haven't found that those viruses are antigenically distinguishable from the
Fujian-like viruses. So we're seeing
low avid viruses have a tendency to group together in the 193/227 group, but
some of those viruses that are not as well inhibited by the Fujian antiserum
are also not well inhibited by any of the other antisera. So we just think those are low avid viruses.
So
I don't ‑‑ in answer to your question, the short answer is we
don't, at the moment, see anything that looks like a definable antigenic
variant from Fujian.
CHAIRMAN
OVERTURF: The one thing that was
troubling to me yesterday a little bit in the data ‑‑ and maybe I
was misinterpreting it ‑‑ it seemed to me that there was a fair
amount of heterogeneity in the serological neutralization of A/Fujian. Is that ‑‑ was that a correct
interpretation? Or do you feel it was
fairly uniform among the A/Fujian-like isolates that in the sera was fairly
representative, fairly neutralizing? Do
you understand the question?
DR.
LEVANDOWSKI: You mean from the human
serologies.
CHAIRMAN
OVERTURF: Yes.
DR.
LEVANDOWSKI: Well, I think we saw some
variability. I tried to point that
out. Maybe I didn't do such a good job. I think generally what we saw for most of
the sera examined in most of the laboratories was that the majority of the
A/Fujian-like viruses are not well inhibited by current vaccine antisera.
CHAIRMAN
OVERTURF: Okay.
DR.
LEVANDOWSKI: But they ‑‑ I
think we can see that there is ‑‑ there is some heterogeneity
there, too, that is a little bit reflective of ‑‑ of what is seen
with the ferret serum. And we didn't
emphasize that, but there are some ‑‑ there were some of the low
reactor type strains that were included in the serologies. And just as they were low reacting in ‑‑
with the ferret sera, they were very low reacting with the human sera as well.
So
it's ‑‑ there is that heterogeneity that is out there, and I don't
know that that can answer your concern except to say that, yes, I think you are
correct in interpreting it as ‑‑ as there is some variability in
the results, not only from lab to lab but between the viruses themselves.
CHAIRMAN
OVERTURF: Is there any further
discussion regarding the issue of the H3N2 strain selection? Again, I will repeat, I think the three
options is either to defer this, to retain the A/Panama strain, or to elect to
proceed to an A/Fujian-like H3N2 strain for the 2004-2005 season.
So
with that, I think we can probably, again, poll the committee for a vote. And this time, to give David a break, I will
start with Ted.
DR.
EICKHOFF: Thank you. I truly think this is the other easy
one. The next one won't be this
easy. But I think certainly based on
the data that Roland and Nancy have presented, I think it's time for an
update. So I would recommend that we
switch strains and move to an A/Fujian-like strain. There are two candidates available that are said to grow
moderately well or grow well in eggs.
There's
another issue that I'll just put out on the table. I think there is an issue of public perception here that we
should be aware of. If we voted to
retain the current A/Panama strain, I think there would be a certain loss of
credibility ‑‑
(Laughter.)
‑‑ on the part of this
panel. Hence, I would vote to update to
an A/Fujian-like strain.
DR.
MONTO: Arnold Monto. I agree.
We need to move to the A/Fujian-like strains. I think that everything is in place for their manufacture, which
I think is probably going to come on second.
And, again, I totally agree that if we didn't do it, we'd have a lot of
explaining to do.
DR.
PALESE: Peter Palese. I vote for switching to the Fujian strain,
which we should have probably done last year.
(Laughter.)
DR.
WORD: This is Bonnie Word. I would agree for the switch to the
Fujian-like strain based on the information presented here.
DR.
MYERS: I agree.
DR.
LaRUSSA: Phil LaRussa. I vote to switch.
CHAIRMAN
OVERTURF: I also vote to switch. I also think there is not just the issue of
credibility, but I think there is a broader issue in terms of vaccine
acceptability. I think when one vaccine
seems to perform poorly, or that's the public perception, I think it hurts all
vaccines. And being a vaccine advocate,
I would really like to make sure that we choose the optimal strain. So I also would vote for a change to
A/Fujian.
DR.
PHILLIPS: Steve Phillips. We vote to change.
DR.
GELLIN: Bruce Gellin. I also vote to change to the Fujian.
MS.
PROVINCE: Cindy Province. I vote to change to A/Fujian.
DR.
McINNES: Pamela McInnes. Given that we are supposed to take into
account data, along with a degree of pragmatism in our decisionmaking, I vote
to change to an A/Fujian-like strain.
DR.
FARLEY: Monica Farley. I vote to change to the Fujian-like strain.
DR.
ROYAL: Walter Royal. I vote to switch to the Fujian strain.
DR.
KARRON: Ruth Karron. I vote to change to an A/Fujian-like strain.
DR.
GOLDBERG: Judith Goldberg. I vote to switch to the A/Fujian strain.
DR.
DOWDLE: Well, I'm not going to start a
new trend at this late date. But ‑‑
but ‑‑ this is Walter Dowdle.
I would like to point out, though, that I think the data that we've seen
so far it's just a little too early to decide how well the Panama strain
performed last year.
You
know, I think we shouldn't leave here without recognizing that we've got a lot
more data coming in, and the studies that we've seen in this country at least
were not designed to really evaluate the current strain. So we need to keep this in mind. I don't think that it ‑‑ based
on past evidence, there's no reason to believe that this was a disaster at all,
because past evidence just simply didn't point that direction.
Having
said that, I think we also always agree to try to have the closest match we can
get, and it's clearly Fujian.
DR.
MARKOVITZ: Yes. David Markovitz. I'd like to agree completely with what Walter said and vote to
switch to the Fujian-like strain.
CHAIRMAN
OVERTURF: Dr. Decker, would you like to
make a comment for industry?
DR.
DECKER: We're ready to get to work
making it.
CHAIRMAN
OVERTURF: Again, that's another
unanimous vote to change to the A/Fujian strain. And we'll proceed onward, then, to the selection for an Influenza
B strain.
It
seems to me, again, there are really three options here. Again, one is to retain the current strain,
the second one is to proceed to substitute with a B/Yamagata-like virus, or,
again, to defer the recommendation. And
so I will now open this issue up to discussion.
Dr.
McInnes.
DR.
McINNES: Thank you. I'd like to ask a question, please, of
Nancy.
Nancy,
the data that you shared about the B strains ‑‑ I think it was
pretty clear that of what you have, the B/Yamagata-like strains are dominating,
and you showed that the two ‑‑ that the strains you have are most
either like the B/Shanghai/361 or the B/Jilin/20. And I still don't know if it's 2003 or 2002. Is it 2003 at the end? That's not my question, but is it
B/Jilin/20/2003?
DR.
COX: 2003.
DR.
McINNES: Okay. And that the data from the October '03
through what you currently have from the three collaborating centers, you had
49 B isolates total, of which 46 were B/Yamagata and three would be
Victoria-like.
DR.
COX: That's correct. And I can add a bit more data that is from
Canada. And so the numbers now are 57
total B's, 52 of which are Yamagata lineage and five of which are Victoria
lineage.
DR.
McINNES: Thank you. So my
question was, given, I think, you also said there wasn't much B activity in, we
presume, the collaborating centers, is it ‑‑ is it a fair
assumption that the collaborating centers have all of the B data we're going to
be able to get for the foreseeable future?
Or is there a likelihood ‑‑ are there viruses that have ‑‑
are in the collaborating centers or could be obtained that have not yet been
looked at?
DR.
COX: We have a few at CDC. But, again, it's relatively few that are in
the pipeline. And certainly whatever
data we can develop within the next few weeks would be available for the
committee, should that be necessary.
It
doesn't look to me ‑‑ we have ‑‑ I was checking the
log-in sheets before I left. And
although we've received a lot of packages, the majority of the viruses are
actually A's, H3N2's. So it would be a
limited amount of information.
CHAIRMAN
OVERTURF: Nancy, of the additional
strains over the 49 that you mentioned yesterday, and now the ones from Canada,
what were the dates of recovery of those viruses?
DR.
COX: They were all isolated between
October and the current time. So
they're all in that most recent time interval that you see on ‑‑ on
our tables that we present.
DR.
KARRON: One more ‑‑ one
more question for Nancy. I know that
sometimes that when we have an A year, we often have a ‑‑ we have B
late in the season. Would we ‑‑
if we were going to have that happen in the northern hemisphere, would we
already have seen that?
DR.
COX: Influenza is full of surprises, as
we all know. But we've been watching
very closely for that second wave of activity, and we have ‑‑ and
we sort of expected that we might see it for Influenza B viruses this
year, since we had Victoria-like viruses circulating last year, quite a few
school outbreaks, and so on and so forth.
But
we haven't seen that increase in the proportion of the total isolates that are
Influenza B. In fact, in past weeks we've seen very few B's isolated in the
U.S., so we're not getting ‑‑ we're not getting that signal that we
usually do when we have that second wave.
CHAIRMAN
OVERTURF: Dr. Palese.
DR.
PALESE: Could I ask whether we could
fine-tune one of the options, so one is retaining it, one is changing, and the
third one was to defer ‑‑ if I remember correctly, looking for the
most recent isolate, the most ‑‑ I think that was the option in
terms of deferring.
I
would like to fine-tune this and say we defer, but really have only the choice
between the Victoria and the Yamagata.
That would give the manufacturer a chance to develop and gear up. They have the old strain ‑‑ to
gear up the new one, and then a deferment would ‑‑ deferring would
mean that we chose to wait, what we get in in the next couple of weeks or more ‑‑
three weeks or four weeks.
So,
in other words, not sort of leaving the option completely open in terms of
deferring, but rather say at the end of that period a decision will be made for
either switching or retaining.
CHAIRMAN
OVERTURF: Yes. This is very similar to what we did with the
A strain last year, actually. Yes.
DR.
DECKER: Just a suggestion of the
refinement of that, or maybe this is what Peter was saying and I didn't
understand it. But it would seem to me
that the data are sufficiently well in hand to make a provisional choice, which
would stand unless CDC, FDA, and the Chair elected to call another committee
meeting.
In
other words, instead of putting off your decision, I wonder if you can make a
decision now, recognizing that you've got X period of time to revisit that,
because we are waiting for reassortants to be made, and so on.
DR.
PALESE: No, that was not what I
meant. I really meant to leave it open,
not to make a provisional decision.
DR.
DECKER: Well, then, my impression was
right, and Peter didn't say that. But I
wanted to.
(Laughter.)
CHAIRMAN
OVERTURF: Dr. Monto.
DR.
MONTO: Yes. I would agree with what I thought was a refinement by Dr. Decker
of the ‑‑ of Peter's remarks, because I think this is a critical
decision, given the fact that, number one, there is so much divergence between
the two lineages, and also the fact that we've experienced in the past
situations where one lineage predominated in one part of the world and the
other lineage predominated in another part of the world.
Correct
me if I'm wrong, Nancy, but I think the B ‑‑ the B/Vics persisted
in ‑‑ in Asia when we were having B/Yamagata a few years back. So the question I would have is: how many of these isolates are actually from
the western hemisphere?
DR.
COX: That would take me some time to
dig through.
DR.
MONTO: Just an impression.
DR.
COX: But the majority of these isolates
are from China and Japan and Thailand, and so on, rather than from the western
hemisphere. So what we're seeing there
is ‑‑ well, we ‑‑ you're absolutely correct in
recalling that the B/Victoria viruses persisted in Asia, and particularly in
China, for a number of years when they were detected nowhere else.
And
then we had the continuing evolution of the Vic-like lineage, and then had its
reemergence in the rest of the world.
It's really ‑‑ because we've had co-circulation of the two
lineages, it's really difficult to know exactly what's going to happen,
particularly based on relatively small numbers. But the signal is there that the Yamagata lineages ‑‑
lineage is predominating actually globally.
CHAIRMAN
OVERTURF: Dr. Goldberg.
DR.
GOLDBERG: Yes. I mean, actually, what you're observing from
the data that you have is that 91 percent of the observed isolates are Yamagata
lineage. And if you just put a 95
percent confidence interval on that crudely, it's compatible with something
between 83 percent and 100 percent, as the true underlying rate would lie
within that interval.
So
I think that with the data we have it would take a lot to overturn it. And if you don't expect very many more of
these isolates, I think we're dealing with an issue that we have to make some
informed judgment, recognizing all of the biases in the way we get the data.
CHAIRMAN
OVERTURF: Yes. If you look at the current data, it sounds
like we've only had three or four B isolates per week over the last
season. And if we were to wait another
two or three weeks, we might have another half dozen at best, unless something
starts up, obviously, but I really think the chances that we will see new
isolates is probably small. And I'm a
little bit perplexed about how you would make a decision, unless you had five
out of six isolates suddenly turn to A/Victoria ‑‑ I mean,
B/Victoria.
Yes,
Peter.
DR.
MONTO: No, I think that's the dilemma,
because we have seen, and almost consistently seen, late B seasons. But the problem is they may be, as Nancy is
saying, that since nothing much is in the pipeline, it may be too late, even
though we do ‑‑ we do see B activity in March and going into
April. It's going to be too late,
really, to ‑‑ given the need for time for analysis and the rest to ‑‑
to be able to say anything that we haven't been able to say today.
CHAIRMAN
OVERTURF: Yes, Dr. Palese.
DR.
PALESE: I just wonder whether these
numbers ‑‑ I feel uncomfortable with 50 isolates when we are told
that there are 20,000 isolates per year.
So is that the number I heard, that overall 20,000 isolates are made per
year? So if you only have 10 percent ‑‑
or, let's say, five percent B viruses per year, we should have 1,000 isolates.
So
I don't understand why we have so few isolates. And is there a possibility of asking WHO and other countries to
help us? I mean, I can see that we have
basically no B in the States. But out
of those 20,000 isolates, which are ‑‑ have been ‑‑ are
being made worldwide, I think we should be able to get some more B virus
isolates.
CHAIRMAN
OVERTURF: Dr. Cox, do you want to
respond to that?
DR.
COX: I didn't think that was a
question.
(Laughter.)
DR.
PALESE: No, it is a question.
CHAIRMAN
OVERTURF: I think that was a ‑‑
DR.
PALESE: If we have 20,000 isolates per
year, and we get a conservative number that we have five percent of Influenza B
virus, there should be 1,000 isolates of B around, and then we could make a
more informed decision.
DR.
COX: Unfortunately, this year less than
one percent of the isolates have been B, so ‑‑ and we don't
necessarily have 20,000 isolates every year.
So, and not all of the isolates are sent to the WHO collaborating
centers for analysis, so we receive a subset of the viruses. You know, we have analyzed what we've
had. We have beaten the bushes, and we
have actually developed ferret sera, as soon as we saw the switch in lineages.
So
we ‑‑ we have really worked hard to develop as much data as we
could within the timeframe between the time we realized that we were seeing the
shift in lineages with relatively few B viruses coming in.
I
personally don't know of the existence of B viruses anywhere outside of the
U.S. that we could ask for. There just
has been quite little activity. I can
see if there is a possibility to get some information, but I certainly couldn't
promise that in three weeks or four weeks, that we would have a significant
amount of new information.
CHAIRMAN
OVERTURF: Dr. LaRussa.
DR.
LaRUSSA: I realize you get a select and
limited group of isolates. But do you
have any information on the lineage of the most severe clinical presentations ‑‑
the deaths and very severe disease?
DR.
COX: We do not, and the information
that comes with the isolates that are sent globally does not include
information about severe cases. The
information that we get from the U.S. sometimes includes that information, and,
of course, when we get information like that we look at those isolates very
carefully.
And,
in fact, this year for the H3N2 isolates that have come from fatal cases, or
serious cases, we have tried to sequence the entire genomes to see if there's
anything unusual about those. So if we
do get that information, we look very carefully. Most of the time we do not get that information accompanying the
isolates.
DR.
LaRUSSA: What about the B viruses? Do you have any information for the B's?
DR.
COX: We have no information this year
that any of these isolates came from fatal cases or particularly severe
cases. Obviously, all of these cases ‑‑
all of the isolates come from patients who sought medical attention, and that's
all we can say.
CHAIRMAN
OVERTURF: Dr. Markovitz.
DR.
MARKOVITZ: Yes. Just, Peter, you were suggesting that we get
data from WHO. But the WHO has already
selected Yamagata-like strain, right?
So anything they have would it seems would support that, I would infer.
DR.
GELLIN: Yes. I have two questions, one is for Nancy, and one is for Michael
representing industry. The Nancy
question is to ‑‑ is there something about the B viruses or these B
viruses that would lead them to be unrepresented in the surveillance
system? Do they not grow well, or is
there some reason why the ‑‑ they may be underrepresented? Or do you think that the numbers out there
reflects the circulation?
DR.
COX: The Influenza B viruses that have
been circulating over the past few years have grown relatively well in tissue
culture. And MDCK cells are actually
used most widely for isolation of influenza viruses generally. And Influenza B viruses of both lineages
have grown reasonably well, so we ‑‑ we wouldn't have any reason to
believe that the B/Vic-like ‑‑ or B/Vic lineage viruses are
underrepresented in our ‑‑ in our sample.
DR.
GELLIN: And my Michael question is a
deja vu from last year. Given that
manufacturing timelines ‑‑ if we were going to entertain a delay
decision ‑‑ what's the drop-dead date by which you would need to
know to proceed with manufacturing strain three?
DR.
DECKER: Well, I ‑‑ let me
turn it around, because I don't think I can answer it the way you posed
it. I have no reason to think that,
say, a three-week delay in making a decision would have any ‑‑ any
plausible risk of an adverse effect on supply or ‑‑ time and/or
availability of supply.
You
start going out beyond that and my anxiety grows, because of the cascade of
factors that have to occur. I'm
reasonably confident that we could spend the next three weeks cheerfully making
H3N2 and worrying about recombinants, and so on. But eventually you're going to have questions about developing
the high growth reassortants, generating the reagents, and on top of that at
some point you're going to start manufacturing the monovalent, and so on.
And
since I have the open mike, let me go on with a comment I wanted to make. It seems to me not only is it true that the
remaining absentee ballots out, if you will, can't ‑‑ are not likely
to be able to change the election, because there are already so many ballots
counted ‑‑ that is to say, B's already looked at ‑‑
that you're not going to be able to shift the vote tally.
But
also, if that were to happen, let's suppose we got five more and they were all
Vic, I think we would still sit here saying, you know, not only is the majority
vote still for the Yamagata, but in addition we've got a population that hasn't
seen the Yamagata vaccine for a long time.
And
if we're unsure, we've got to go for the new strain, because there's ‑‑
if we're wrong, there's at least the hope of some benefit from prior years'
campaigns with the other strain, whereas if we stick with the current strain
you don't have that going with you. So
it's hard for me to imagine that delay will actually buy anything useful.
CHAIRMAN
OVERTURF: Yes. Dr. Goldberg was first.
DR.
GOLDBERG: If we assumed ‑‑
to continue what I brought up before, if we assume that we got 10 more B
isolates, and that they were all not Yamagata, you still would have observed 63
percent of them, and you'd still be more than 50 ‑‑ pretty certain
if the true rate was over 50 percent would fall within that interval.
So
that I think it would be very hard to overturn these data in a short amount of
time, unless the rate completely changes of accrual of the isolates. I mean, that's really the hooker, and so I ‑‑
I mean, I guess it was really the drop-dead date, with an expectation of what
you might assume.
You
think five. I was more generous and
said 10, to see how far we could push it.
But it doesn't seem like you would really overturn the view in this
short amount of time.
CHAIRMAN
OVERTURF: Yes, Dr. Karron.
DR.
KARRON: Just a comment I wanted to make
to address something that Michael Decker said.
I am particularly concerned, given the point that Marty Myers made
yesterday, about responsive of young, naive children to Influenza B.
So
whether there has been prior experience in the population with the other strain
or not I don't think is as relevant for those young children who are
naive. So I think it's ‑‑
it is ‑‑ if we can, particularly incumbent on us to choose the
right strain to protect that population.
CHAIRMAN
OVERTURF: Is there any ‑‑
yes.
DR.
McINNES: And just following up on Ruth,
because I also was very concerned about the pediatric population that, Marty,
you and Dr. Turley put on the table, because the mean age was pretty low, and
they really were the younger infants.
And
I just want to confirm, because my ‑‑ dendrogam reading is
sometimes impaired.
(Laughter.)
On
the table that you showed, the HI antibody response to the B component in that
pediatric population, you had an n of 25, and then you show ‑‑ one,
two, three, four, five different antigens.
Am I reading this correctly, that only the B/Hong Kong, which is close
to the vaccine strain, comes from the B/Victoria, and that those other four are
B ‑‑ or B/Sichuan/259/2003 is also from the B/Victoria, right?
So
that the B/Jilin, the B/Washington, and the B/Jiatsu are all from the
B/Yamagata, which matches, then, the very poor cross-reactivity that we're
seeing.
Thank
you.
CHAIRMAN
OVERTURF: Yes. Dr. Levandowski.
DR.
LEVANDOWSKI: And I should emphasize
that the other data that we had from the other pediatric study showed the same
thing. It was identical in the respect
that there was a good response against the vaccine type strain, but not against
the B/Yamagata lineage strain that was ‑‑ it was the same kind of
night and day, even though the children were somewhat older. And a few of them might have been
immunologically primed, but the data show the same thing, really.
CHAIRMAN
OVERTURF: Dr. Eickhoff.
DR.
EICKHOFF: Ted Eickhoff. Basically, I subscribe to Judith's way of
looking at this. I think the numbers
now clearly weigh in favor of a switch to B/Yamagata. However, if indeed we were to see a late B outbreak this spring,
and it were 100 percent A/Vic, that would make me worry a great deal.
I
think the odds of that happening are, frankly, remote. But who knows?
CHAIRMAN
OVERTURF: Dr. Palese.
DR.
PALESE: Can I just address also ‑‑
I mean, flu has its bottlenecks genetically.
So if suddenly, really, 10 ‑‑ I mean, hopefully it won't be
more ‑‑ of the B/Victoria would come up, I think that would weigh
much heavier despite statistics, because it would genetically say that one
which makes it, and, therefore, I think it would be very worrisome, and suggest
that the next wave would be a B/Victoria rather than B/Yamagata.
CHAIRMAN
OVERTURF: Dr. Monto I think was first.
DR.
MONTO: And just to continue the
statistical discussion, I think we are dealing with clusters ‑‑
with cluster sampling here.
DR.
GOLDBERG: Yes. It's very biased accrual and sampling as
well, so that what you don't know is whether you're getting them all in the
right sequence from the same location.
So that I think that we're in a small numbers business.
And,
unfortunately, it all rests on what Dr. Eickhoff brought up, which is really,
what is the likelihood that we will really see an outbreak of B somewhere, that
we will have some new isolates clustered in time and in place, so that we would
really be able to interpret the data. I
think that's the crux of the issue, and anything beyond that is ‑‑ it's personal
probabilities of what you feel the likelihood of that is.
CHAIRMAN
OVERTURF: Dr. Karron.
DR.
KARRON: A question back for Michael
Decker, which is, how helpful would it be to industry to make a provisional
recommendation but with a mandated, you know, rereview by the committee at
X time of what the choice of strain is.
Is that helpful in any way? Is
that not helpful?
DR.
DECKER: The only thing that I was
thinking was that if we think it's probably a settled issue, we'll want to
reserve a chance to ‑‑ for a change, leaving it at ‑‑
at the administrative level, rather than having to convene the committee in a
conference call, which depends upon schedules and will be on a fixed time,
might have some advantages. That's all.
Because
if ‑‑ if, for example, over the next two and a half weeks the
answer becomes obvious, either we need to have a meeting or we don't need to
have a meeting, obviously, the CDC and FDA, they can just transmit the ‑‑
if it's not have a meeting, they can transmit the information to industry, go
ahead and start making this one, whatever was chosen.
If
you ‑‑ if you set a meeting date, if you think it's necessary to
set a meeting date, I think the consequence of that will be that people will
not take action until that meeting date.
I mean, otherwise there is ‑‑ the fact that you chose to do
it that way sends the signal that anything produced in that period of time is
at risk.
So
it's a small difference. But if ‑‑
if ‑‑ in a case like this where I think we're reasonably sure, I
just want to raise that possibility as one option for the committee.
CHAIRMAN
OVERTURF: Dr. Levandowski.
DR.
LEVANDOWSKI: Just so you know, there
was the anticipation that there might be a possibility of deferral, as there
was last year, and so there is a meeting date that's already been set. And I think it has already been
announced. Maybe Bill Freas could fill
us in on the details on that.
DR.
FREAS: Administratively, I believe the
date that has been selected is March 17th as the latest date that this
committee could convene and make a decision.
And that would be by teleconference.
CHAIRMAN
OVERTURF: Dr. Gellin.
DR.
GELLIN: I mean, we're here ‑‑
we're here at a fixed point in time, and our ‑‑ you know, weighing
a decision ‑‑ the viruses continue to circulate. Surveillance continues to be ongoing. So I guess I wonder if we should have a
brief discussion about plan B. Should
there be a plan B?
And
if ‑‑ I mean, this is, I mean, Michael's worst nightmare, but I
think we should have a discussion about if something were to change later in
the year, for which we wanted to either reconsider or have another discussion,
what would we do? I mean, if ‑‑
sort of it ‑‑ and pick your number of isolates or outbreaks that
occur, and then there is some shift for which we think that there might be a
need to have a different virus to provide better protection next fall,
recognizing that the large ‑‑ large manufacturing processes may
have begun.
What
would we do? Are we nimble enough to do
that? Or are these all or nothing
decisions, and we're stuck with our decision, whether it's today or March 17th,
and then potentially watch another season go by where we would have wished we
might have done something different.
CHAIRMAN
OVERTURF: Yes, I'd like to hear a
discussion regarding that from industry.
Each ‑‑ this is now the second year this has come up, and
the issue always is: is it an all or
none decision? It sounds like we make
the decision at a point in time A, and we make another decision at a point in
time B, but it didn't sound like last year ‑‑ and I'm not sure this
year ‑‑ that anything is really reversed by the second ‑‑
by the second call, because it's just too short a period of time to make a lot
of changes and decisionmaking.
So
it sounds to me like somewhat an irreversible decision. The only thing that happens is is that
there's a delay in manufacturing ‑‑ in starting the B process, if
we don't make a final decision today.
DR.
DECKER: Yes. Dr. Gellin raises an interesting question with a number of angles
to it. First of all, let me comment
again. I don't see any problem with our
putting off the B decision for three to four weeks, because I think we'll be
fully occupied with H3N2 in the meanwhile.
So
this year, this time, I don't see a particular problem with that. That's not always true. But the question really is, what if a
freight train comes running down the tracks in July? What happens then? Well,
either we've got ‑‑ either you're talking about a pandemic freight
train, in which case, Bruce, you know as well as anybody in the country what we
do then, and how ‑‑ what we figured out what to do.
But
the simple answer to that is that there are some high-level meetings that made
some fundamental decisions. Do we ‑‑
do we stop all current production and devote all resources to generating
monocomponent pandemic strain? If it's
a serious enough threat, that's what we'll do.
And
then, everything that's in the hopper at that point, a decision will be made,
between the government and academia and industry of what to do with what's in
the hopper. Do we distribute it? Do we not?
But you'll stop making it.
That's if it's a pandemic. I
think that's pretty clear.
But
let's suppose you have something else.
It's not the pandemic, but ‑‑ but you have a situation, as
we had a decade or a decade and a half ago, where you've got this new strain
that comes on very strong, and there's a desire to do something about it.
I
think the simple fact of the matter is you've got no answers that work. There are lots of choices. They've all been tried, and none of them
were satisfactory. For example, you can
make a monovalent supplemental strain, and by the time you get it made and
distributed nobody wants it.
You
can alter your current formula, in which case you're throwing away months of
production, and that will impair both the timing and availability of vaccine,
and you'll end up with a better vaccine that arrives to people later in lower
quantity.
So
if you do some type of net calculus of the benefit to the country, you've not
clearly benefitted. And we faced a
variant of that last year, where this committee agonized over the choice of
strain, and everybody here wanted to use Fujian, but there was ‑‑
but the majority of the committee felt that it wasn't practical to try to go
that way, because of the impact on timing and supply of vaccine.
So
we reluctantly went with the next best choice, and we ended up with what was
predictable, which is a vaccine that didn't prevent ILI very well, but which ‑‑
which, if past history is any guide, will turn out a year from now when we have
all of the data to have been pretty good at preventing death and serious
morbidity, which is basically what we hire the vaccine for in the first place.
So
was our decision last year wrong?
Probably not, but we don't know yet.
So what if the same thing happened again this year? What would we do? I just don't think we've got a good answer, because we're ‑‑
the virus moves on its timeline, which is not necessarily consistent with the
manufacturing timeline.
If
it rises to a pandemic and you want to stop making the regular vaccine, that
can be done. But when it falls in that
gray zone, and you don't want to throw away the current vaccine, but you'd like
something more, you probably can't get something more done using any technology
known to man in the timeframe available before the virus comes and goes.
CHAIRMAN
OVERTURF: I'm concerned that ‑‑
still, that the argument that we will not see a difference in three or four
weeks is probably very good. I would
prefer, if we plan a meeting three to four weeks from now, that it only be to
rereview what we've looked at.
But
I can't ‑‑ I can't conceive of ‑‑ of unless ‑‑
unless we have a major outbreak of B/Vic someplace in the next three weeks, I
can't imagine how this is going to change the decision. And we're just ‑‑ I think we're
stuck with a low numbers game for this year, and that's ‑‑ that's
the game.
Yes.
DR.
DOWDLE: Walter Dowdle. I tend to agree with that, that you already
have now a Victoria ‑‑ I mean, sorry, a Hong Kong strain that grows
well, I mean, in the current vaccine.
You've already got that, so that's nothing new. I mean, you could have that available.
But
to me it's inconceivable that this committee would not want you to start right
now and to work as hard as ‑‑ I mean, to send a strong signal that
we need to start adapting the Yamagata-like strains for growth of a
vaccine. I don't see how we can send
any other signal except we need to start right now.
So
the question is, three or four weeks from now, is ‑‑ is you either
with Yamagata or you go with Victoria.
And we're all saying the likelihood of going with ‑‑ with
the Hong Kong-like strains, Victoria-like strains, are pretty slim.
So
I ‑‑ I would agree. I'm not
sure what ‑‑ waiting is going to do that much good, except to say ‑‑
just to say, well, in the last minute there's possibility to reverse, but
that's pretty remote.
CHAIRMAN
OVERTURF: Yes, Dr. Markovitz.
DR.
MARKOVITZ: Yes. Just following up with what Walter just
said. I wanted to just specifically ask
Roland and Nancy ‑‑ sorry ‑‑ I think you guys have made
it fairly clear, but where do you come down on the issue of the likelihood of
any significant real data emerging in the next four weeks?
I
think, Nancy, you said very unlikely, but I'd just like to hear from both of
you how likely it is that we're going to find anything new in the next four
weeks.
DR.
COX: I think that unless, as others
have discussed, unless there is a large outbreak somewhere, large outbreak of
Victoria lineage viruses somewhere, it is unlikely that we would be changing
our view of what's going on. And it
doesn't appear at this time that there is a lot of B activity out there.
I
suspect that we could do something such as develop an understanding that if
such an outbreak did occur that information would be transmitted to the
committee immediately. I don't know if
we've had such an arrangement in the past, but that I think might help reassure
the committee that if anything did happen they would have that information as
soon as possible and then the committee could reconvene or ‑‑ or do
what would be necessary to look at that new data and reconsider the options.
CHAIRMAN
OVERTURF: Actually, that's a plan that
I would actually favor, would be to leave it up to the individuals who continue
to do the surveillance to make the committee aware of any significant
changes. If we want to define a
"drop-dead date," or industry wants to define a drop-dead date when
we can't change, although we do already know we have the current Vic strains.
So
I don't think that's a huge issue, if we make a decision to change. But the only decision would be predicated on
extremely good surveillance that changes that picture, and I ‑‑ I
have difficulty knowing that that would happen. But it would seem better to leave it up to the surveillance folks
to give us that information.
Yes,
Dr. McInnes.
DR.
McINNES: I wonder if I might ‑‑
I'm a little bit uncomfortable with a decision and then, if necessary, to be
sent the data and review it. And I
wonder if there is the consideration of a provisional recommendation, which
sends the strong signal, and a meeting on March 17th with whatever data we have
in hand, to either confirm that recommendation or to change that provisional
recommendation.
I'm
a little bit uncomfortable with a recommendation, unless I hear something
otherwise. And so I wondered if there
was ‑‑ would be an opportunity to convene and get whatever data
there would be by March 17th, and either then, you know, confirm that
provisional recommendation or change it.
CHAIRMAN
OVERTURF: I'd have to hear from Roland
or Bill on this. I would think there
would be several ways to transmit the information to the committee, either via
mail or e-mail or a variety of other ways.
And unless ‑‑ and we would have to convene an emergency
meeting if there was ‑‑ people could leave the date open.
DR.
LEVANDOWSKI: If you want me to answer,
I ‑‑ I think we have had similar situations where we've had, at the
‑‑ when we used to routinely have two meetings, we were trying to
avoid having multiple meetings for this purpose, but anticipated that it might
be necessary.
In
the past when we had such experiences, there were provisional recommendations
that were made, and then they were either confirmed at the next meeting, and
usually they were confirmed at the next meeting, in fact. The original decisions of the committee ‑‑
recommendations of the committee I think actually were the ones that were the
ones that stuck.
But
I think that this ‑‑ it's already set up that ‑‑ it's
the possibility of having that meeting, and unless the committee didn't want to
do it, I think it would probably be better for us to have that ‑‑
have that meeting in such a situation so that we do just transmit the
information and make sure that it was understood.
CHAIRMAN
OVERTURF: Dr. Goldberg.
DR.
GOLDBERG: I would support the
provisional recommendation and having some kind of confirmatory meeting,
because we all know from events of the recent years, the unthinkable can
happen. And it's a protection against
that in the decisionmaking, as long as that date ‑‑ the March 17th
date or whatever the committee date is will still meet the manufacturing
deadline. It's to protect against the
unthinkable.
CHAIRMAN
OVERTURF: Dr. Karron, yes.
DR.
KARRON: I'm trying to just figure out
whether what industry ‑‑ their interpretation. Clearly, there is much interest in the issue
of Yamagata. It's hard for me to
imagine that whether we did provisional or if we even just formally deferred,
that industry isn't seeing the positive signal towards Yamagata and wouldn't be
looking at it as the strong candidate.
And would they not be doing the preparation anyway?
And
I'm just wondering how important it is, the actual category we put this into,
because I think I agree having some protection against an overwhelming outbreak
should be there. But does it matter
where we say "deferred" with a strong feeling towards Yamagata or
provisional Yamagata in terms of what ‑‑ what you will do in the
next three or four weeks.
DR.
DECKER: No. This is actually ‑‑ this aspect of it is relatively
easy this year. I mean, I'm feeling
pretty comfortable with the idea ‑‑ more comfortable than in some
prior ‑‑ the idea of deferring the B decision until the March 17th
date, or somewhere around that.
My
comment before was more just towards the ‑‑ being reasonable to
everybody's lives and schedule. For
example, if you knew right now today that there would be no further isolates,
would you still schedule a March 17th meeting?
Probably not.
So
if it turns out on March 17th there were no further isolates, do you still want
to have a meeting? Or if CDC
communicated that by e-mail, might we elect not to? That was the only nature of my question. It wasn't an industry capacity issue.
But
let me turn it around for a second, just so that we've ‑‑ although
I don't think it's ‑‑ although it's not applicable this year, it
could be applicable next year. I'm
feeling very comfortable from the industrial point of view about our deferring,
if we wish, the B decision until the 17th, because we've got a clear-cut H ‑‑
we've got two clear-cut decisions, and the one we decided on that involved a
choice ‑‑ a change ‑‑ the H3, we've got everything we
need in hand to get to work on it.
But
let's suppose that the facts were transposed, and you knew exactly what you
wanted to do with B, but we didn't have the materials to work with yet. And you didn't know what you wanted to do
with A H3N2, where we have the materials.
That would be a real problem for us, because then you would be telling
us we couldn't actually make stuff for three or four weeks. This year that's not a problem; we can make
stuff.
So
we ‑‑ I ‑‑ I believe there is only a threat to
production if the ‑‑ if something happens that delays a decision
beyond the point where we would actually start manufacturing rather than
getting ready.
CHAIRMAN
OVERTURF: Dr. Monto.
DR.
MONTO: Let me create a strawman for a
minute, and say that in the next week we have, in some place which has not had
flu for the last few weeks, which is rather unheard of in the middle of the
winter, a major outbreak in the United States of a virus in the B/Vic lineage.
We
still have the situation where we know that in children, who are the main ones
who get Type B infection and get in trouble with Type B infection, the
situation that you either produce antibody to one or you produce antibody to
the other. And you're not going to be
producing antibody to both.
How
would we move at that time? And will it
‑‑ will we move any differently if that happens?
CHAIRMAN
OVERTURF: We'll discuss a quadravalent
vaccine again, which we do every year also.
(Laughter.)
DR.
MONTO: That's why this is more biology
and ‑‑ than policy.
CHAIRMAN
OVERTURF: Yes.
DR.
DECKER: We had a wonderful discussion
on quadravalent last year. But I just
want to remind you ‑‑ I want to join the mathematical group with
Dr. Goldberg and point out that 80 million doses at three serotypes equals 60
million doses at four serotypes. So had
we made that decision last year, we would have had a more interesting vaccine
for which 20 million Americans would have been told, "You can't have it,"
who actually got vaccine last year.
CHAIRMAN
OVERTURF: Yes. It's a very important point to reiterate
each year, that you reduce your doses considerably when you go to the
quadravalent vaccine.
Yes.
DR.
MARKOVITZ: Although if we really ‑‑
if we really had quadravalent vaccine every year, you'd ultimately increase
production probably, right? So ‑‑
CHAIRMAN
OVERTURF: Hearing no answer to Dr.
Monto's question, I think we should probably proceed with a vote. And I ‑‑ to me, I think we have
three options still, and the only issue is whether you wish to preface the
change to a B/Yamagata with a provisional change, or whether you wish to simply
vote for a change.
Obviously,
the other two options are to retain the current strain, and the third option is
to defer completely any decision today and plan for a review in the future.
So,
yes, one ‑‑
DR.
KARRON: I just want to make sure that
I'm clear. So that if we vote for a
provisional change, there will be a mandatory meeting on March 17th at which
we will review the data?
CHAIRMAN
OVERTURF: There will either be a
mandatory meeting or there will be information conveyed that would ‑‑
would negate the need for that meeting, one or the other.
Is
there any further discussion? Yes, Dr.
Levandowski.
DR.
LEVANDOWSKI: I think I'd like to
reiterate that if there's a provisional recommendation, I think we'd want to
have the next meeting. I don't think we
want to just do things as an informal sending of information. I think we'd rather have it, as we're doing
this, as an open public kind of presentation.
CHAIRMAN
OVERTURF: I guess it would be a very
short meeting if there was no new data, or if the data confirmed the selection.
Yes.
DR.
PALESE: If one of the choices is
deferring a decision, could that be also tied into with a request for more
data? In other words, I don't know
whether we have a way of doing this, but to really ask that a major effort is
made ‑‑ and I don't know by whom ‑‑ that we get
worldwide data, particularly from the summer season in the southern hemisphere.
CHAIRMAN
OVERTURF: Well, I ‑‑ to me,
the deferral is an automatic request for more data. But I ‑‑ in terms of getting more data, part of it is
‑‑ is whether isolates are available, and they simply may not be.
Yes.
DR.
COX: Just ‑‑ we have the
isolates from the southern hemisphere for the previous season. Their season ‑‑ their upcoming
season doesn't actually peak until July, and so there is ‑‑ so we
do have all of the information from the previous southern hemisphere season,
and it's in the package. But we don't
and won't have the new information in time to really help us out.
CHAIRMAN
OVERTURF: Dr. Eickhoff.
DR.
EICKHOFF: May I make a motion to ‑‑
CHAIRMAN
OVERTURF: You can make a motion.
DR.
EICKHOFF: ‑‑ get us
started? I move that we recommend ‑‑
we provisionally recommend switch to a B/Shanghai/361/02-like virus, and that
the target date for making that final is a teleconference on March 17th.
CHAIRMAN
OVERTURF: Do I hear a second for that
motion? Okay. Dr. Markovitz has made a second.
With
that, I think we'll just go around the room from Dr. Eickhoff and request
discussion. Dr. Dowdle.
DR.
DOWDLE: I wonder if he would accept a
slight amendment.
(Laughter.)
And
that is that we recommend the Yamagata-like strain, and reserve the right to
reconsider that at the March meeting, which would give a very strong signal,
and would say that's the way we're going.
And unless something comes up that strongly disagrees with this
decision, then we can take that step.
It
is ‑‑ I admit, it's the same thing, except that I think it does
have some ‑‑ some implications here for the manufacturers and for
FDA.
DR.
EICKHOFF: I have no problem with that.
CHAIRMAN
OVERTURF: So the motion has been made
to vote on a recommendation to change to the B/Shanghai-like virus in the
Yamagata lineage, and with an option to review that and change it, if
necessary, at the March 17th meeting.
Is that correct?
This
time we'll start with you again, David, and ask for your poll.
DR.
MARKOVITZ: I think it's pretty
easy. I agree with Drs. Eickhoff and
Dowdle that we should do exactly that.
So I think it's probably being slightly overcautious, because it seems
very unlikely that we're going to end up changing our mind.
But
as caution is a very good thing to do with influenza, I think it's a very good
motion. And hopefully we'll ‑‑
or probably we'll have a very short teleconference that day. Everyone has it blocked off on their
calendar anyway, so it's a good idea.
DR.
DOWDLE: Thank you. Walter Dowdle. What can I say but agree?
(Laughter.)
DR.
GOLDBERG: Judith Goldberg. I agree. I think that there is an extremely
low likelihood that the decision will be changed, though, but it is a good
protection.
DR.
KARRON: Ruth Karron. I agree.
DR.
ROYAL: Walter Royal. I agree with the change to the B/Shanghai
strain with the teleconference on March 17th.
DR.
FARLEY: Monica Farley. I slightly prefer it to be called a
provisional decision, but setting that aside I vote in favor of the
recommendation to change with the option of reconsidering.
DR.
McINNES: Pamela McInnes. I prefer the philosophy behind provisional
recommendation, with an urging for whatever data can be brought to the table on
March 17th to be done, and a reconsideration of those data with either an
affirmation of that provisional recommendation or a change.
MS.
PROVINCE: Cindy Province. I agree with Dr. Eickhoff's motion.
DR.
GELLIN: This is Bruce Gellin. I agree with the motion but would like to
put in a placeholder that if there is a lot of new data that is unveiled
between now and then, we have a better understanding of where it has been.
DR.
PHILLIPS: This is Steve Phillips, and
we agree with the recommendation.
CHAIRMAN
OVERTURF: I also agree with the
recommendation. I ‑‑ I
can't foresee that we're going to change this, but I ‑‑ I think
it's a reasonable precaution.
DR.
LaRUSSA: Phil LaRussa. I think we know what we're going to
know. But given that the only harm is
to the ‑‑ inconveniencing the committee members with another vote,
I agree.
DR.
MYERS: Martin Myers. I agree with Dr. Eickhoff's recommendation.
DR.
WORD: Bonnie Word. I agree with Dr. Eickhoff's and Dr. Dowdle's
recommendation. I'm just a little
confused as we went around the room. I
thought there was only one question on the table, and then I start hearing
these other responses. So I don't
understand how we're ‑‑ how we're ‑‑
CHAIRMAN
OVERTURF: I'm interpreting it as one
question, so ‑‑
DR.
WORD: Okay. Because I was, like, there was one question on the floor.
CHAIRMAN
OVERTURF: I can restate that if you
want, yes.
Dr.
Palese.
DR.
PALESE: I would like to sort of see the
word "provisional" decision, and to me that is like deferring. But I think it would ‑‑ I think
we should really make the final decision on March 17th.
Now,
I don't know what the Chair ‑‑ how he counts my vote then.
(Laughter.)
CHAIRMAN
OVERTURF: I can discuss it with you
later.
DR.
MONTO: Arnold Monto. I agree with Dr. Dowdle's revision of Dr.
Eickhoff's original motion.
CHAIRMAN
OVERTURF: Dr. Eickhoff.
DR.
EICKHOFF: I agree.
CHAIRMAN
OVERTURF: If you understand this better
than we do, Dr. Decker, you are willing to go ahead and try and interpret
it. We'd like your opinion.
DR.
DECKER: No better, but hopefully no
worse. The ‑‑ once again,
industry is grateful to the committee for its efforts.
CHAIRMAN
OVERTURF: Well, I think we are actually
scheduled for a break, and we are about 45 minutes early. The break was scheduled for 15 minutes, so I
will plan to go ahead and take a break now and reconvene at 10:15.
Thank
you very much.
(Whereupon, the
proceedings in the foregoing matter went off the record at 9:59 a.m. and went
back on the record at 10:25 a.m.)
DR.
FREAS: As we take our seats, I just
want to let the committee members know that, again, we have to schedule
meetings months in advance. And so on
your desk will be the Federal Register announcement of the teleconference on
March 17th, and, of course, it's scheduled from 1:00 to 5:00 ‑‑
1:00 a.m.?
(Laughter.)
It's
scheduled from 1:00 p.m. to 5:00 p.m., and it's on this little calendar as
well. So the date and the time are
set. It will not last as long as we
initially anticipated last February, but please mark that on your individual
calendars.
CHAIRMAN
OVERTURF: Dr. Gellin would like to
clarify an issue that he brought up.
MR.
GELLIN: As far as data that may be
hiding, I think that the ‑‑ I think that what I said before may
have been misinterpreted, because we had a pretty robust discussion about how
the world gets its data, where it's been, the processing thereof. And, therefore, the idea that there is data
out there hiding seemed to me, you know, remote at best. So what we're really talking about is, you
know, the review of incremental data that comes forward.
So
my intention was, really, to ‑‑ to clarify that I thought that we
would have little to talk about at the next meeting, not that there was
somebody with a big closet full of stuff out there. And I won't elaborate on people who do find closets full of
things.
Thank
you.
CHAIRMAN
OVERTURF: The other discussion that
came up during the informal discussion during the break was the issue about the
quadravalent vaccine again, and I guess sometime we need to ‑‑ to
reintroduce it.
It
sounds to me like if we were to consider a quadravalent vaccine we'd have to
first of all make that for a recommendation for a future year, and make it a
generalized recommendation, and then would have to consider strains each time,
if we were going to maintain production as we have in the past.
Yes,
Dr. Decker.
DR.
DECKER: Well, and if you're serious
about it, the other thing you would have to have is ‑‑ I think is a
commitment that you would then stick with a quadravalent for a decade, or
something like that, because as Dr. Markovitz pointed out, if industry knows
that the demand will be there and has time to adapt, the capacity can be built. But nobody builds a factory that's not going
to be used year after next. So there's
got to be the commitment to sustain the capacity.
CHAIRMAN
OVERTURF: I assume there is no further
discussion, then.
The
next issue on the topic is, again, an issue that's been brought up a number of
times and was discussed recently, again, at the recent NVAC meetings, and
that's the use of mammalian tissue culture for reference strain isolation.
So
the FDA has invited a discussion about that this year, and we'll start out with
Dr. Ye.
DR.
YE: Good morning. I think probably we remember that almost
exactly one year ago A/Fujian/411 virus was not chosen as the vaccine
strain. Part of the reason is that this
virus was isolated from cell culture rather than from eggs.
So
today's talk we tried to ‑‑ and I try to explain why this virus was
not chosen, and is there any possible solution for not using this cell culture
driven virus for the vaccine.
And
this presentation actually was based on a preparation ‑‑ a position
paper initiated by our Division Director, Jerry Weir, and had input by
others. And this ‑‑ my ‑‑
the title of my presentation is, "The Preparation of Reference Influenza
Viruses in Mammalian Cells," which is what ‑‑ FDA's
perspective.
There
are two objectives for this presentation.
The first one is to review the issues associated with the source of the
reference influenza viruses. Another
objective is to discuss the possible strategies for use in ‑‑ for
using mammalian cell lines to prepare influenza reference viruses.
I
think since the 1940s inactivated influenza viruses vaccine has been prepared
in eggs. The reason is that by using
eggs we have a good production of influenza vaccine, which eggs provide the
reasonable virus yield.
The
candidate vaccine viruses originally isolate in surveillance labs use eggs as
opposed to use mammalian cells, which is a global consensus within WHO national
regulatory authorities, as well as manufacturers.
However,
over the time, many surveillance labs has come to rely on ‑‑ use cells
for isolation of influenza viruses from clinical samples, for the reasons of
robustness and convenience, even though such isolation are not used as
reference viruses.
And
this slide shows the isolation of circulation viruses from clinical samples in
national influenza centers all over the world.
There are two methods for isolation of influenza viruses from clinical
samples. One is use cell culture.
Such
cells are not qualified or certified for ‑‑ there are three cells
that have been used for isolation of influenza viruses from clinical
samples. One is MDCK cells, which is
canine kidney cells. And these cells
have been used for quite some time for isolation of propagation of the
influenza viruses.
The
second one is VERO cells. This cell is
monkey kidney cells, recently introduced for isolation or propagation of the
influenza viruses. Only a few labs ‑‑
surveillance labs ‑‑ use such cells for isolation of influenza
viruses from clinical specimens.
The
last ‑‑ for the MDCK cells and the VERO cells are continuous cell
lines. And the last one is the chicken
embryo kidney cells, which is the primary cell lines. Only a few labs use these cells for isolation of a virus.
And
the last one ‑‑ next one is eggs.
In the beginning of the influenza vaccine production, the majority of
the labs used eggs for isolation of influenza viruses, because of the cell ‑‑
the eggs that you have to ‑‑ the limited supply of the eggs and
also the convenience of isolation of the influenza viruses.
So
fewer and fewer labs use this method for isolation of the viruses. Actually, in the United States, there are no
labs or surveillance labs that use this method for isolation of influenza
viruses from clinical samples.
This
slide shows the isolation rate of influenza viruses from clinical samples. This clinical sample has been prescreened by
using more sensitive methods, such as immunofluorescence and rtPCR. And the table shows the isolation rate of
the influenza viruses from prescreened clinical samples.
And
the Y bar shows the percentage of isolation, and X bar shows the different
method. The first two shows the ‑‑
from MDCK or VERO cells, and the last one is for eggs. And the red bar shows the isolation rate for
Type A influenza viruses, and the yellow bar shows Type B.
As
you can see, the MDCK cells and the VERO cells ‑‑ there is not too
much difference in terms of the sensitivity of isolation of the virus, even
though MDCK cells is relatively sensitive than VERO cells. But overall the two cell lines looks similar
for isolation of both viruses.
The
yellow bar shows the B viruses isolation.
As you can see, there is not too much difference between cell lines and
eggs for isolation of clinical samples.
Where there is dramatic difference in isolation of Type A influenza
viruses, you can see that only less than 20 percent of the isolation rate for A
in eggs, where more than 60 percent of the isolation rate for Influenza A
viruses. So this is why majority of
surveillance labs use cell line for isolation rather than use eggs.
Because
we use ‑‑ we use cells for isolation of influenza viruses from
clinical samples, there are some consequences.
Yearly strain selection can be negatively affected by requirement for
egg isolates as seed viruses, which resulted in delaying recommendation for
vaccine composition, such as last year, and also resulted in altering
composition for vaccine strain because of availabilities.
In
addition, a delay in availability of strain selection during the pandemic
situation, it could be disastrous consequences.
This
slide shows the licensed influenza vaccine in United States. The two licensed influenza vaccines in the
United States ‑‑ first one is inactivated influenza virus vaccine,
which commercially available for more than 50 years. And this vaccine is produced in eggs and delivered by parenteral
injection.
And
the next one is a live attenuated influenza virus vaccine, which is recently
licensed. And this vaccine produced in
specific pathogen-free eggs rather than regular eggs, and delivered by
intranasal inoculation.
This
slide shows the influenza vaccine under development, divided into two major
categories. One is a cell-based,
inactivated virus vaccine in MDCK cells or in VERO cells, which I just
mentioned before. And another one is
DNA vaccine or recombinant protein such as to ‑‑ to express the
protein in virus protein in insect cells.
Okay. Now I'll just go through the reference and
seed virus development. The first WHO
global surveillance system, such as national influenza virus ‑‑
influenza centers in ‑‑ all over the world to provide the reference
of viruses which isolated from clinical samples use eggs as opposed to using
cells.
Then,
international influenza center would provide reference viruses to WHO
collaborating centers, such as CDC in Atlanta, London, Melbourne in Australia,
or Tokyo in Japan. In WHO collaborating
center, they provide reference viruses, include high growth reassortant viruses
to manufacturers.
Then,
manufacturers will develop preparatory seed viruses from egg isolate, which are
recommended by WHO or local authorities.
And, finally, regulatory agencies will accept the reference of viruses
and approve seed viruses for use in licensed vaccine preparation.
And
this slide shows the summary of the preparation of reference and seed
viruses. As you can see from here, to
provide a seed ‑‑ reference of viruses or seed viruses, it required
a teamwork of globally. The first one ‑‑
WHO surveillance centers in national influenza center will provide the virus
which isolated from clinical samples from using eggs.
Then,
they sent this virus ‑‑ reference viruses to WHO collaborating
centers. If this reference virus
recommended is ‑‑ the vaccines ‑‑ vaccine candidates,
then they will send this to manufacturers as well as to regulatory agents.
Manufacturers
then will develop their own preparatory seed viruses, and then sent back to WHO
collaborating centers or back to ‑‑ or to regulatory agents for
evaluation of the seed viruses.
So
this slide shows that, really, to develop seed viruses or reference viruses it
requires a lot of, you know, organizations work.
And
this slide shows why we use eggs for isolation of influenza seed strain. As I mentioned that this is a safety ‑‑
egg isolates has a safety record for more than 50 years, and possible exclusion
of some adventitious agents from clinical samples, because using eggs rather
than some ‑‑ adventitious agents may grow well in tissue cultures
but not grow well in eggs, and also leading to high yield in vaccine
production.
In
addition, this method has been validated for inactivation of common chicken
viruses in vaccine process.
Now
I show to you the ‑‑ the pros and cons for consideration of
mammalian cell lines for isolation of seed strain. The problem for using mammalian cells for isolation of influenza
viruses from clinical specimens is ‑‑ are following. The first shows the pros, the
advantage. It's more robust than eggs
for primary isolation of Influenza A viruses from clinical samples ‑‑
I mentioned to you earlier.
Secondly,
it's less selective pressure than in eggs for isolation of influenza viruses
from ‑‑ with alternative receptor specificity. In general, influenza virus, like other
viruses, it does not like switch from one species to another one. They have a sacrifice to adapt in the
different species.
So
by ‑‑ by ‑‑ because of human sample, the virus
originally grow in the human samples, will more likely grow well in the same
mammalian cells, so they have less pressure for the antigenicity variation.
Another
reason is a practical reason, because of majority of WHO global surveillance
centers have such cells for isolation.
So they are familiar with and they are comfortable for use in such cells
for isolation of the virus.
Now
the problem ‑‑ the problem is, of course, that we have limited
experience in influenza vaccine development and production. One such as the isolation ‑‑ the
isolation of the virus or the isolates may not necessarily grow well in eggs,
because they are in mammalian cells first.
Then,
more importantly, there are some issues related to the use of mammalian cells
for isolation of seed viruses for the possible contamination of adventitious
reagents, as I mentioned that a lot of a virus will grow well in mammalians
cells rather than in eggs.
And
this slide shows the regulatory requirement and guidance for ‑‑ for
the related ‑‑ related to use of mammalian cell lines. This ‑‑ the first one is 21 CFR
610.18 regarding cell ‑‑ use of cell lines for manufacturing biological
products.
Even
‑‑ although this guidance is ‑‑ is for using cell lines
for vaccine production, but what I'm ‑‑ I'm talking about is the
use of cells for isolation of influenza viruses, but they share same concern,
because of use ‑‑ even though you use a cell for isolation viruses
rather than use the cells for production of flu vaccine.
The
general requirement for the cell line is to have to ‑‑ the cell
line has to be identified by the history, such as where the cells come from
from a dog or from a monkey, and also have to show the pathogenic history, what
condition of the cell is being passed, is there any possibility introduce
advantageous into it, what kind of lab condition you are using to maintain such
cell line.
Another
thing is to have ‑‑ to describe with respect to the cytogenic
characteristics, such as the chromosomes ‑‑ how many chromosomes
and the morphology of such cells as well as tumorigenicity, and also includes
oncogenicity of the DNA from these cells, and also have to be characterized
with respect to in vitro growth characterization and the type ‑‑
life potential such as, you know, it takes how many hours to divide it and
what's the time expended, how many passages you pass before the cell dies or it
can be passed forever, so on and so forth, and have a test for the percent of
detectable adventitious agents.
And
more details of the regulation ‑‑ regulatory requirement and
guidance is the point to consider in characterization and cell line used for
production for the product ‑‑ for producing biologicals. And this is published in 1993; however,
currently under the revision by Office of Vaccine ‑‑ Vaccines and
Research and Review, and which provide relatively detailed and additional
guidance on preparations and standards for characterization and the
qualification of cell substrates and virus seeds.
An
additional regulatory requirement and guidance is as follows. One is WHO technical reports series
regarding requirement for biological substance, and also the ICH guidance, QC5,
has some details regarding the ‑‑ using cells for production of
influenza vaccine or the evaluation of the cell lines.
Another
one is European Medicine Evaluation Agency guidance, and also provides some
information regarding the ‑‑ using the cell line for influenza
vaccine production.
Okay. Now we move on to the strategies for
consideration of use of mammalian cell lines for isolation of reference
viruses. The first one actually kind of
‑‑ we are ‑‑ is we are using a similar method for H5 ‑‑
H5N1 virus isolation. First is retain
the clinical samples of the initial isolation in national influenza centers,
and then forward the samples to select ‑‑ select WHO collaborating
center for reisolation in a qualified cell line.
As
I mentioned, this is similar to the current procedure, except for using a cell
line for reisolation rather than use eggs.
Of
course, in order to achieve this, we have to have a suitable cell line for
reisolation, so preferably to cell bank would be produced and qualified for
distribution to selected centers for reisolation.
And
since the original samples directly cultured or in the ‑‑ in the
cells, so any contamination in the original samples may amplify in the cell
lines. So the further purification and
adaptation of a cell line for vaccine production in eggs could be considered,
if necessary.
The
second one is the use of reference viruses direct isolated on the cell line
which are not characterized or qualified.
So as you can imagine, the cell line is not qualified, neither qualified
or characterized, so any contamination will be there will be ‑‑
will be amplified. So it would require
the purification of reference viruses to be acceptable.
For
instance, you know, possible plaque purification on the specific pathogen-free
chicken kidney cells, and have to be evaluated if the contaminate or potential
viruses can be eliminated by such purification. And, of course, the resources and the infrastructure for
purification would be necessary, because who is going to do it and going to evaluate
such method.
The
third one is to use the reference viruses isolate in characterized and
qualified cell line. Of course, in ‑‑
to achieve this, it would require the production and qualification of
preferably the cell bank for distribution to national influenza center.
Remember
that national influenza center, their purpose is not just for isolation of
influenza viruses, those other viruses, and maybe have some other viruses was,
you know, handled in the same lab. So
the contamination would be quite high if they do not handle cell well.
So
the first rule is we have to choose the cell line such as MDCK cells or VERO
cells, other cells such as MRC5 cells for qualification, and then, more
importantly, the maintenance of the quality control of the distribution to
avoid additional ‑‑ introduce adventitious agents into the
qualified cell line.
Then,
the further purification or adaptation of cell isolates for vaccine production
in eggs wouldn't be necessary. It would
be considered if it's necessary.
And
the last one is to use the reverse genetic method and qualified cell line to
generate new reference viruses. You may
remember yesterday from Nancy and Phil, as well as Linda Lambert's talk, to use
reverse genetics for preparation of 85 N 1 for pandemic preparation. They used this ‑‑ such method.
So
this ‑‑ of course this would require the production and
qualification of cell bank for reverse genetics, because we use these cells for
licensed vaccine production rather than for pandemic preparation.
Another
one is by using this method, I think it's ‑‑ because when you
extract viral RNA for ‑‑ during reverse genetics, you really use a
very harsh way to purify the RNA from the viruses. So a lot of contamination usually is limited by this
procedure. So once you purify the RNA
for construct ‑‑ the construct for reverse genetics, so usually
it's quite a good way to eliminate concern regarding the contamination of the
original sources.
And,
of course, the problem will be accepted on the technology and intellectual
property issues, which may not permit near ‑‑ in the near term.
All
right. The conclusion is that the use
of influenza seeds viruses obtained from non-egg sources may be acceptable if
adventitious agents in the original isolation or in the cell lines used for
isolation can be addressed.
A
second one is investment in the resources and infrastructure is necessary.
And
the last ‑‑ lastly, because ‑‑ I mentioned these are
global issues, you know, to ‑‑ we have to have consensus ‑‑
global consensus, which we seen WHO, national regulatory authorities, as well
as the manufacturers, regard ‑‑ regarding use ‑‑
regarding the issues to be addressed for implementation of this method.
Thank
you.
CHAIRMAN
OVERTURF: Are there questions or
discussion for ‑‑ yes, Dr. Markovitz.
DR.
MARKOVITZ: Yes. I was curious if you could just describe in
a little more scientific detail exactly how you certify a cell line. I mean, I understood the general principles,
but what do you actually do? I mean,
what are the techniques involved?
DR.
YE: To certify a cell line, as I
mentioned in the guidance, first you have to ‑‑ to show the cells
is really what you're talking about. If
it's from a canine, then you have to show this is from a canine.
In
some cases in the lab or in the ‑‑ in organization, when they pass
the cells sometimes they release some cells which are contaminated and ‑‑
but not from canines, some cells such as the contaminant, and they have to show
that, really, the cells you're talking about.
And,
secondly, if ‑‑
DR.
MARKOVITZ: I'm sorry. Do you do that genetically? I mean, you ‑‑
DR.
YE: You can ‑‑
DR.
MARKOVITZ: Do you sequence part of the
DNA of the cell?
DR.
YE: You can sequence it, and there is
some enzyme you can detect. They have a
difference in ‑‑ between different species, so you can tell the ‑‑
you know, some enzyme approach, and you can identify to tell difference. And also, have to be addressed, any
contaminations because some viruses may not be detectable by current method,
but is hidden in the cell lines, but may be passed on through the vaccine or
the virus ‑‑ the seeds viruses.
So
you have to show the ‑‑ you really handle the cell lines well. And also, and the ‑‑ if the
cells cause a tumor, or the DNA causes a tumor as well, and also there are
other viruses, you know, in ‑‑ integrated into the DNA chromosome
of the cells, you have to ‑‑
DR.
MARKOVITZ: How do you do that,
though? I mean, how ‑‑
because which viruses do people look for, and how do you do it?
DR.
YE: Here I cannot ‑‑ it's
this thick ‑‑ page by page to go through that. I ‑‑
DR.
MARKOVITZ: No. But, I mean, just in general, do you do a
PCR looking for known viral sequences?
Or what do you actually do to eliminate it? Because that's obviously a huge concern with this.
DR.
YE: There is a huge protocol to
evaluate it ‑‑ say, use animal ‑‑ newborn animal to
show if this causes tumor, just by inject the cells or you isolate it, DNA to
the animals, see if anything happened, or culture in the cells, sensitive
cells, depending upon which viruses you are looking for. So you have to use the sensible ‑‑
suitable cell lines for particular virus.
DR.
MARKOVITZ: Maybe ‑‑ but
which viruses, though, are people actually looking for when they ‑‑
it can't be that long of a list. What ‑‑
DR.
YE: I probably have to refer this to my
colleagues.
(Laughter.)
DR.
MARKOVITZ: Oh, I guess it can be a long
list.
DR.
YE: There's a lot ‑‑ a lot
of ‑‑
DR.
MARKOVITZ: So how long is the list?
DR.
YE: I have a short memory, but I cannot
remember at all.
DR.
MARKOVITZ: How long is the list
exactly? And how do you do it?
DR.
YE: As long as you can list.
DR.
MARKOVITZ: So what do you do
practically. I mean ‑‑
DR.
YE: Yes.
CHAIRMAN
OVERTURF: I think Dr. Levandowski would
like to try to clarify it.
DR.
LEVANDOWSKI: Right. I think Zhiping on his slide where he
indicated the CFR position on this, it sort of shows you generally what needs
to be done. It doesn't tell you
specifically, because there may be more ‑‑ more than one way to
skin a cat. But generally identified by
history ‑‑ as you mentioned, you start out by saying where you got
the cell line and how it was handled before you got it, if there's anything
known about it.
Most
places ‑‑ most people get their cell lines either from another
laboratory or they get it from ATCC or from the European culture collection, or
one of the standard culture collections.
So that's how you start out.
But
there's a lot of information that goes with that in the passage history as to
what media were used to propagate the cells throughout their life, what other
excipients might have been present, and all of those things. And all of those things in the documentation
are part of the information that is being looked for to understand what might
have happened to these cells or where they actually came from.
And
it can't ‑‑ simply that information can be enough to tell you
whether the cell line is appropriate or not.
But he also mentioned or went over the fact that these need to be
described by cytogenic characteristics, chromosome analysis, isoenzyme analysis
to differentiate species. There are a
number of ways to do that chemically and biochemically, and these days you
probably could use genetic techniques to try to get to some of that answer.
And
then, you know, finally, the information about detectable microbial agents ‑‑
how long is the list? The list is as
long as you'd like to make it. There
are both biological and other types of methods like PCR to try to get to
information about what type of contaminating microbial agents might be
present.
So
some non-specific tests are done that are meant to catch any kind of virus that
could replicate in a tissue culture.
Usually there are several tissue cultures ‑‑ certified
tissue culture cell lines that are used to try to replicate viruses that might
be present.
And
there are ways to try to show that viruses that are inferring might be there,
you know, that don't necessarily show cytopathic effect but may be able to
show, by another method, that they interfere with a marker virus.
And
then you can use the ‑‑
DR.
MARKOVITZ: How do you do that? Excuse me.
How do you do that?
DR.
LEVANDOWSKI: You inoculate the tissue
culture with your interfering virus, and then see whether you get ‑‑
actually, you inoculate the tissue culture with your non-interfering virus and
see if you get heme absorption ‑‑ or hemagglutination, for example,
is one way to do it for that particular marker virus that you're using, to see
whether there's interference.
There
are also inoculation of animals. I
mean, it's a fairly extensive protocol, as Zhiping said. It's not a simple matter to do this
qualification or certification.
DR.
MARKOVITZ: Yes. I mean, the reason I'm asking ‑‑
I'm not an alarmist about this or anything, but you know when you hear things
are certified the immediate question is, well, what makes these really safer
than anything else? And obviously,
there are going to be some viruses nobody ever knows about, but ‑‑
but the question I guess really is, which ‑‑ you know, I mean,
apparently this is something other people know, but, I mean, how many viruses
really ‑‑ I mean, so there's two questions.
One
is you're actually, you know, trying to look for any virus, any cytopathic
activity, right? So, but the other
question is, what viruses in particular might one actually find in these cells
that would eliminate them? I mean, is
there like ‑‑ are there five ‑‑
DR.
YE: I think ‑‑
DR.
MARKOVITZ: ‑‑ or how does
that work?
DR.
YE: In general, it's by using current
method you can ‑‑ as much as you can to detect as much as possible
of the virus you could do it. So I
think to make it safe down the road.
You
may not know now, and later after a few years we have a new method and say,
"Hey, there is X virus in there, and it causes this in humans." So I think we'd rather do more complex work
in the beginning to ensure down the road we ‑‑ you know, that we do
not introduce some viruses to the human by ‑‑ through the vaccine.
DR.
MARKOVITZ: What do you want to see in
the chromosomes, by the way, Roland?
Were you hoping for 46 or what ‑‑ what's the ‑‑
what are you looking for in chromosomes?
DR.
LEVANDOWSKI: You're hoping for the
number that it's supposed to have for the particular species it should be. So if it's not the right number for the
species ‑‑
DR.
YE: Right.
DR.
LEVANDOWSKI: ‑‑ it's not
the right cell line.
DR.
YE: Right. Different cells have different ‑‑ usually, the cell
line is a continued cell line. That ‑‑
you know, it's totally off. It's not
regular ‑‑ they don't have regular chromosomes there.
DR.
MARKOVITZ: A lot of cell lines, though,
have ‑‑ you know, that are in common use have a lot of
chromosomes. So that's I guess ‑‑
sure, you're trying to check to make sure it's the right species, but do you
want ‑‑ I mean, how much ‑‑ when you're certifying
something, do you tolerate extra chromosomes?
DR.
LEVANDOWSKI: It need to be
explained. I mean, there may be other
things that happened in handling the cells as well, so there ‑‑ if
there are extra chromosomes out of what should be expected for the description
of the cell, then you, again, question whether it's actually what it's supposed
to be.
DR.
MARKOVITZ: No, I don't mean that. I mean, when you're talking about safety
issues, one of the questions is, you know, is there some sort of oncogenic
virus or whatever, or transformed cell that in some way might be
dangerous? And the question is: are there ‑‑ you know, is that
okay to have extra chromosomes, as long as it matches what the cell line is
supposed to be.
DR.
YE: Well, I ‑‑
CHAIRMAN
OVERTURF: Sorry. There's ‑‑ Doctor? Yes.
There's probably a switch at the top there.
DR.
EGAN: Okay. Sorry. Bill Egan from
Office of Vaccines. I think one of the
problems is one can't give you a simple exact answer about what you need to do
that's going to cover every single situation.
Obviously, it's impossible to test for every single virus that ever
existed. That you can't do.
But
if you're, for example, going to use a mammalian cell line, you're certainly
going to test for Hepatitis A, Hepatitis B, Hepatitis C, HIV. You're probably going to do ‑‑
and you're going to be doing those by PCR.
We
generally are going to test for retroviruses.
You're going to do reverse transcriptase PCR analysis to look for
that. There are ‑‑ you'll
be doing tissue culture to look for any cytopathic effects for unknowns. So there's a variety of things. Some cells are continuous, and they're going
to have a distribution of chromosomes, and they'll be in a certain range
because tumorigenicity, for example, of VERO cells are going to change by the
number of passages.
So
you ‑‑ so what you're going to look at, and the level of concern,
is going to be specific to a particular situation. Now, in addition to all ‑‑ you know, if you have a
vaccine produced in the cell and you can't guarantee some certain clearance of
cells from the final product, then you certainly want to know something about
the tumorigenicity of those cells and the oncogenicity of those cells, looking
at, you know, the cells, and looking at DNA.
They're
probably looking at DNA as a function of size.
There's a whole variety of things, you know, that you're going to do
depending on those cells, what they're used for, what you can do during the
manufacturing process. Whether
something is inactivated or not inactivated, what you can validate would be
clear during that inactivation.
That's
one of the reasons why we're very concerned also about this history. You know, what have they been through will
give you some idea of what they could be contaminated with that you might want
to look at. What else has been in the
lab?
We're
also ‑‑ and this wasn't mentioned ‑‑ we're very ‑‑
one of the things we're very concerned about are the agents of the
transmissible spongiform encephalopathies.
So if you have a cell line that was grown that was using calf serum or
fetal calf serum, where did that come from?
Can you document it or not?
What
else do you know about the cell line?
If it were contaminated, is that cell line able to propagate the agent
of that TSE? And on and on and on.
But
the only way to really answer your question is to give ‑‑ come in
very, very specific. For example, I
want to use VERO cells four, and then we can discuss it. Otherwise, you know ‑‑ and the
bottom line, it's going to be all driven by the science.
DR.
MARKOVITZ: Thanks. That's what I was wanting to hear. Thanks.
CHAIRMAN
OVERTURF: Dr. Dowdle, and then Dr.
Monto.
DR.
DOWDLE: In regard to the logistics of
providing characterized or certified cells to the laboratory, so that the
laboratories have those available, I would just like to ‑‑ to
remind you that the polio virus network of 150 laboratories throughout the
world have such a system in place now, so that every laboratory has a liquid
nitrogen bank ‑‑ cell bank.
Many of these laboratories, by the way, are in developing
countries. In fact, most are in
developing countries.
The
cells are provided by NIBSC, and Phil, in fact, may want to comment on this
later in his discussion. These are
highly characterized cells. They are
set up ‑‑ the labs are set up in such a way that there's a very
high QC component of the work, so that the cells are actually used only for 15
passages, discarded, they start again to cut down mycoplasma. All of these issues have been taken into
consideration.
Now,
you'd have to notch it up a little bit in terms of the strains that are
provided, but all I'm saying is the logistics are there. In fact, even now you could start using that
through the polio system. But it's very
highly controlled, and it can work. And
the logistics ‑‑ the cost of this is relatively small. It's not as big as we might think that it
is.
DR.
YE: Thank you. I think you addressed a good question for
practical reasons. It's achievable if
the lab do what it's supposed to do to maintain the cells, the cell bank for
the isolation. So it is achievable, so ‑‑
but in order to do it, we have to evaluate it to make sure the cells are
properly handled and no additional virus is going to be introduced into it.
CHAIRMAN
OVERTURF: Did you respond specifically
to that, Dr. Egan?
DR.
EGAN: Stick this thing back on. Bill Egan.
Yes. The issue, of course, here
that may be a little bit different is we're talking about a virus that's going
to be used for further manufacture. I
mean, what you said is perfectly reasonable, and it is doable. But, you know, it's ‑‑ you have
to set it up, and you have to continue to monitor.
So
the other approach is to have, you know, a small group of centers that would
just simply reisolate. And if you're
talking about plaque purification or something like that, it's not unduly
burdensome to set that up, and, you know, which becomes the easier system, you
know, would ‑‑ that might be possible. You know, we could just, you know, see.
CHAIRMAN
OVERTURF: Dr. Monto.
DR.
MONTO: I think in examining the various
options we need to bear in mind the logistics of reisolation, retaining of
specimens, sending specimens for reisolation to central laboratories, presence
of certified cell lines at national influenza centers, with the assurance that
they are being handled appropriately for isolation, etcetera.
I
think it's clear that we do have one option which would be ideal if
intellectual property issues are taken care of, which is, I don't think, our
consideration right now. But there is
another one that is on the table ‑‑ number two ‑‑ that
I think we need some further information about how easy it is taking strains
directly isolated in cell cultures, unapproved cell cultures, to purify them
using existing approved techniques and readying them for vaccine production. How easy would that be? What would the timeline be in your
estimation?
DR.
YE: I think we're really ‑‑
you're talking about option number two, right?
DR.
MONTO: Yes.
DR.
YE: Because I have ‑‑ over
here it's hard to hear the question. As
you can see, the cell is not certified, and then there's a possibility the
contamination will be not only from the original sample, but also the cell
itself. You don't know what ‑‑
what's going on in that cell, so extensive purification needs to be validated
to make sure, say, if you spike a model virus you can show this virus can be
eliminated by plaque purification.
So
it's ‑‑ a lot of work needs to be done to ensure that no ‑‑
the virus has not, you know, contaminated in your seed virus. Probably is a short answer.
CHAIRMAN
OVERTURF: Dr. Levandowski.
DR.
LEVANDOWSKI: I just wanted to remind
everybody that we are anxious to hear from the committee all their ideas and
options. We're not sure that we have
all of the answers here. We've laid out
some considerations, but maybe there are others that the committee would have
also. And, you know, just ‑‑
we really do want to hear what you all are thinking about in terms of what
we've laid out here.
DR.
YE: I think, as Roland Levandowski is ‑‑
as he pointed out, we are not just providing answers. Actually, we are, you know, asking for more questions or
input. So it's maybe beyond that four
options. Maybe if you have more
reasonable, you know, strategies can be, you know, under discussion.
CHAIRMAN
OVERTURF: Do you have a question, Dr.
Karron?
DR.
KARRON: Actually, a couple of
things. First, I just wanted to
clarify, Arnold, what you said when you said that there's an ideal option, but
there are IP issues. I assume you're
talking about number four, but I want to, one, make sure that that's the
case.
DR.
MONTO: Yes, I was.
DR.
KARRON: Okay. And then I guess my second question has to do with, as you
mentioned, we're currently using strategy number 1 for H5N1. You did say that in your talk. Is that ‑‑
DR.
YE: Yes. But I don't know if it was the right thing to say or not. But it's kind of different, because you use
the qualified cell line for pandemic ‑‑ okay. Go ahead, sorry.
DR.
KARRON: I understand that. I guess my question would be I'd like to
know, one, how well that system is working for isolation of pandemic strains in
practice. And to have some discussion
about what the barriers would be. I
assume key barriers for implementation of that kind of a strategy for use for
non-pandemic influenza.
DR.
YE: I cannot answer the question on the
IP issues. But in terms of using
reverse genetics, I think it's ‑‑ as Phil Minor talked about
yesterday, that is a wonderful method, and you can get what ‑‑ any
kind of ‑‑ the virus in any condition can ‑‑ you can
isolate ‑‑ go ahead.
DR.
EGAN: I was going to say maybe have Dr.
Minor give his presentation and the NIBSC perspective, and then come back to
this issue more globally on discussion of what people think they might be able
to do, what things might be acceptable, what are the pitfalls of various
technologies, whether it's even possible to consider using an isolate that came
through an unqualified cell line or something like that.
DR.
MONTO: Just a point of
information. Aren't we using for the H5
number four as well, the reverse genetics?
DR.
YE: As I understand it, yes. But that's ‑‑ it's for pandemic
rather than use the licensed vaccine.
Nancy?
DR.
COX: Just to clarify, for the H5
vaccine reference strain production, we started out with an egg isolate that
was sent to us from one of the national influenza centers in Hong Kong. And so we had an egg isolate, and it's also
possible in many cases to get the original clinical material and then obtain an
egg isolate or a cell culture isolate from that original clinical material.
So
it takes extra time and there are extra logistics involved, but then you can
start out with something that you're not concerned about at all and go on to
the next steps.
CHAIRMAN
OVERTURF: Dr. Royal.
DR.
ROYAL: Thank you. In discussing the various options for how to
incorporate mammalian cell lines into isolating viruses, are we also looking at
how the flow chart that you've shown in slide 11 would be impacted?
It
appears as though ‑‑ well, I guess it's the fact that industry
receives seed virus from both the coordinating centers and from the FDA I
guess, from the regulatory agencies, and given the fact that in your cell lines
you'll ‑‑ you have a more permissive system, you'll have
potentially lots more isolates to deal with, how might the flow of material be
impacted as it's collected and distributed?
DR.
YE: This is ‑‑ the flow
chart actually is for ‑‑ refers to the egg isolate. For cell isolates, maybe the flow chart will
be different.
DR.
ROYAL: Should that be discussed?
CHAIRMAN
OVERTURF: I'm going to ask for one more
question, and I think we should then probably proceed to Dr. Minor's
presentation. But Dr. Myers has one
more comment.
DR.
MYERS: Yes, it's a comment more than a
question. I think it's clear we need to
expand our repertoire for being able to develop candidate seed viruses. But I think strategy number two, which was
the one that we discussed at such length last year, is really not a practical,
pragmatic strategy for the development of the seed virus in a timely ‑‑
timely fashion or without compromising the potential safety of a vaccine.
And
I think that's ‑‑ so I don't think that's really a practical
consideration as a strategy for seed virus development. I didn't think that last year either.
CHAIRMAN
OVERTURF: With that thought, why don't
we hear Dr. Minor's presentation, and then we can readdress the issue.
DR.
MINOR: Okay. Thanks. Thanks very much,
indeed. Vaccines are extraordinarily
sensitive kind of biological agents, as I'm sure you're all aware. I mean, they are given to people who are
healthy, and the intention at least is to keep them healthy.
So
there's an enormously conservative approach to how vaccines are actually
produced. And even a fairly
straightforward kind of vaccine, like, say, extracellular pertussis or
something like that, if you call that straightforward, is really approached
with extreme caution and extreme care along the line.
And
it's quite simple, if you like, compared to what you see with influenza,
because an influenza vaccine is ‑‑ firstly, it's a new product
every year, because sooner or later somebody is going to update something at
some stage, so you really have to consider the whole thing one a yearly
basis. So many of the vaccines that are
around at the moment have been going for 20, 30 years, and so on. Okay?
So you have a lot of experience in how to do them.
Flu
vaccines are far more complicated and far more ‑‑ far more
delicate, if you'd like. So you really
have to be aware of the fact that there is a deep conservatism in the vaccine
industry.
As
a truism, influenza vaccines depend on the isolates. If you haven't got the isolates, you haven't got the vaccines,
and that's the way it works at the moment.
And they depend on viable isolates at the moment as well. It may be that with reverse genetics you
could actually get away from viable isolates, but you're not in that stage yet
by any means. Okay?
The
isolates that you get may have other viruses present in them, and they may have
come out of it because of viruses that are coexisting in the nose of the
patient from which you got the original swab.
They may also have viruses in them resulting from their passage as
they've been carried in the field and as they've appeared in the various
laboratories that you just saw in the ‑‑ on some of the previous
slides. They may have picked something
up along the way. Okay.
Now,
the reason why I think people are quite happy with flu vaccines is that there's
a great deal of experience with them.
Over about 50 years they've been produced in eggs, and there really
doesn't seem to be much of a problem with them. I remember having a serious discussion in a bar with a
manufacturer once where I said, you know, the good thing about flu vaccines is
that, you know, they seem to be reasonably okay.
And
he thought this was quite funny. It was
a good, appetizing jingle. You know,
flu vaccines, we haven't killed many people, you know.
(Laughter.)
I'm
not sure it would be quite so good as that.
I mean, it's better than that.
It's better than that.
I
mean, they have been used for over 50 years, and they have a good track
record. I'm surprised, you know, they
don't do much damage. So whatever
you're doing it's okay. Right?
The
fact is that, quite honestly, you don't know what you're doing. You're taking materials from patients who
are out in the field who ‑‑ who have Lord knows what living up
their noses, and you're injecting that into eggs, and most of these eggs that
the isolates would be done in are not specified pathogen-free, so there may be
other things growing in there. Okay?
There
may be contamination of the product by other viruses, but so far as you can
tell this has not been a problem.
Okay? And by the time you get to
the end product, it's not a problem.
Fifty years worth of clinical experience says that this is a very safe
product. Potentially it's a very
effective product that you don't actually see the kind of difficulties that you
have.
But
it's a very, very complicated and complex chain of events that leads from
somebody having flu to somebody actually having a vaccine which then goes into
somebody else along the line. Okay?
And
the regulatory view ‑‑ at least the NIBSC perspective ‑‑
is that if that's what you've got, a very complicated system where you're not
quite sure what's going on, if you change anything in the procedure you've
really got to be very, very careful indeed.
You must be very cautious about any changes that you put in there. Okay?
Now,
in the United Kingdom we had a certain amount of discussion in the clinical
virology area about what kind of cells or systems people were actually using
for detecting viral ‑‑ virus and disease, if you'd like. And you have to bear in mind that many of
these clinical labs at least are not just concerned with isolating flu.
I
mean, they are also interested in isolating other kind of respiratory viruses
as well. And it may be that there are
other kind of cells which are more suitable for isolating other respiratory
viruses. There are certainly other
kinds of cells which are more suitable for isolating enteric viruses.
There's
a cell line called L20B, which is one of the things used in the polio network
that Walt just mentioned, which is a mouse cell transected with a polio
receptor site. Really, it's extreme
good for isolating polio, but it's pretty useless for isolating anything
else. Okay?
So
depending on what you're trying to do, you will use a different kind of cell
type. And in the United Kingdom what
used to happen was that there were primary monkey kidney cells that were
actually prepared and distributed from a central source, more or less at least,
as a very, very good, highly sensitive catch-all kind of cell culture system
that clinical virology labs could use for anything. Okay?
I
think that supply has more or less dried up now, but, I mean, I may be wrong on
that. Maybe Marie can comment on that
if necessary.
There
are other things ‑‑ MDCKs and VEROs, which were just mentioned, and
possibly other cells as well. This is
just from the United Kingdom where we have a rough idea of what we can actually
look at to see what's being isolated.
Out in the wide world I don't know what they use, although MDCK and
VEROs are clearly in there, and kidneys as well. There may be other things as well. Okay?
And
I'm not sure that I would want to handle a virus which had been isolated on a
baboon kidney somewhere in the middle of Africa, for example. I'm not quite sure what else would actually
be in there. Okay? So I think that's an issue that you might
want to bear in mind.
The
other thing is, as well as saying you have different cells to actually look at,
the way the cells are carried is ‑‑ is really quite variable, if
you'd like. It was pointed out that you
have to ‑‑ if you're looking at a certified cell line, you have to
have some characterization on it to show that it's what you think it is.
Cells
lose sensitivity on passage. This is
well documented and well known, and it may well be a real phenomenon. It may also be that they lose sensitivity
because they get contaminated with things like mycoplasma, for example. There are viruses which may be present in
serum, which they could actually pick up and become infected with in a totally
subclinical way, if you'd like. So in a
way that you wouldn't actually see that they were infected, but nonetheless the
virus would be in there. Things like
BVDV, for example, can possibly do this.
And
there's certainly a porcine kidney line, which people have used for titrating
yellow fever vaccine in ‑‑ which is chronically infected with the
hog cholera virus. Okay. Nobody knows ‑‑ nobody cares
about this, because they know about it.
But there may be cell lines out there which ‑‑ which have
similar kinds of viruses in them which you don't know about. Okay.
What's
more, my cell is not necessarily the same as your cell. My MDCK cell is not necessarily the same as
yours. My VERO is not the same as
yours, and so on. Okay?
They
also require a great deal of skill in maintenance, and this was something which
emerged I think in the UK network. I
mean, that ‑‑ it really was a ‑‑ quite an effort for
the individual labs to maintain their own cell lines. And what has been tried at least is to send out cell cultures
from a central facility and really that will improve things enormously. So it really does say that there are
difficulties in maintaining these cell lines in real life.
Now,
the polio network that Walt referred to really seems to have quite a good
handle on this and how you actually deal with it, and you go back to your
reference preparations repeatedly. When
the issue of flu isolates first came to my attention, which was about 10 years
ago, I mean, I thought, why don't we just tap into the polio network. And I suggested this to WHO who said,
"Well, there are actually different labs." And so it's like, you know, I mean, you ‑‑ so there's
a certain amount of turf wars to go on here.
Okay?
I
mean, it does seem to me that you could use the polio network in precisely this
way, and it seems a shocking waste to me that this beautiful system has been
set up, okay, and you're not going to use it for other things as well. And maybe it will be in the long run, but I
don't think it is at the moment, which is a bit of a shame. Okay.
Right. And they vary in quality, if not in name, as
I say here.
There
are a number of different vaccine types which are potentially in the
offering. There are three here which I
will talk about. The egg-grown inactivated
vaccines are the most common, at least in Europe, and I guess over here as
well. So eggs are the basis of the
production, and you have to bear in mind that these eggs are almost certainly
not specified pathogen-free.
So
they will come from commercial flocks, if you'd like, they are not examined
carefully to make sure that they are totally free of any virus that may be
there. Okay? So this is actual routine production of influenza vaccine. And this is the way it's been going on for
50 years, and, as I said in my initial opening remarks, there will be no issues
with that. There is no difficulty with
that. It's perfectly okay to do this,
because the clinical results are satisfactory.
Okay?
I
have to say, if this kind of product came out as a brand-new kind of product
nowadays, I think it would have a bit of a rough time actually.
There
are other issues. Cell culture-grown
vaccines, which have been inactivated, which again was referred to in the
previous presentation, the issue is here slightly different, because your cell
cultures may actually be growing viruses that your eggs are not. Okay?
I mean, the assumption that people have worked on is that the eggs act as
a sort of microbiological filter to some extent, which may or may not be true,
but nonetheless it may be true.
So
if you're growing your materials in cell cultures, such as VEROs, you may be
growing viruses which you wouldn't normally grow in an egg system, and,
therefore, you would worry about it. At
least you'd want to consider it very carefully.
And,
finally, there's the egg-grown live vaccines, which I won't talk about.
One
of the arguments that frequently comes back is, well, the product is
inactivated anyway, so what's the problem?
Now, the inactivation process that's used most commonly involves
formaldehyde, and regulators who say inactivation of viruses by formaldehyde
have a little shudder and they think SV40, which I'm going to mention in a
minute. Okay?
But
it's very good at inactivating influenza.
In general, in my experience at least, the processes have not really
been validated, at least in data that has been presented to me, to show that
they will inactivate other viruses as well.
Okay? And where it has been done
it's rather less impressive than you'd like it to be. Okay?
So,
I mean, there are precedents for this kind of partial activation of potential
virus contaminants. Okay? So you can't necessarily rely on the fact
that you've inactivated your virus with formaldehyde to say you got rid of
every virus that might be there.
Okay? You can't trust it. It helps, without a doubt, but you can't
trust it. At least I don't trust
it. You may, if you wish.
Finally,
there are a couple of examples where ‑‑ where this I think becomes
a real issue. I mean, you can say,
well, it's a pretend issue because there may be viruses in there. But who cares? I mean, chickens aren't going to affect me too much, are they?
And
here are two issues which repeatedly come back to bite the regulators on a
regular basis more or less. In the
1950s, inactivated vaccine was produced according to the Jonas Salk method,
where you treat the live virus preparation with limiting concentrations of
formalin over a long period of time.
Okay? And you have to be very
careful how you balance the formalin and the treatment with inactivating the
virus and not destroying the antigenic properties. So it's a very carefully controlled process. Okay?
The
virus was at that time grown on rhesus macaques kidneys, and what was not known
was that a virus called SV40, which is a polyomavirus, which causes tumors in
rodents, and so on, was actually a very frequent silent contamination of these
kind of monkeys. Okay? When you start moving toward the monkeys you
get a cytopathic effect, and it becomes obvious that you shouldn't use that
cell culture. Okay? But at this time, with the rhesus macaques,
it's a silent infection and you couldn't actually see anything in particular.
SV40
is less easily inactivated by formalin, and that is polio. And what the consequence of that was that ‑‑
from about 1955 to 1962, probably everybody who had three shots of polio
vaccine in this country, or in my country, or anywhere else, probably had a bit
of live SV40 stuffed into them as well.
Okay?
Now,
you could say that's a plus or it's a minus.
Okay? Because if the SV40 is
inactivated, what you've done is you've basically immunized them against SV40,
right? So they're not going to get a
tumor, right? You could say it's a bad
thing because they've been given live SV40 and they weren't banking on
that. Okay.
For
a long time there were some quite serious epidemiological studies done on this,
which suggested that there was no issue involved, and that the studies weren't
that terrific, frankly. They were too
short term, and they involved too few people, and they didn't look at the
people who have actually had the contaminated material. They looked at other stuff. Okay?
But
nonetheless, there's a certain element of contentment about it that made it
look like everybody got away with it.
And then, in the 1990s, there were publications from Michele Carbone and
others, many others in fact, to say that you can identify SV40 sequence in
certain kinds of human tumors. And they
include things like mesotheliomas and ependymomas and osteosarcomas, and stuff
like that. Okay?
It's
still unclear what this actually means, and it's still highly unclear where it
came from. I personally doubt very much
whether it came from the polio vaccines that we used in the 1950s, and they
certainly don't come, in my view, from polio vaccines or anything else that's
actually made now, because we have evidence that they are clean. Okay?
But
nonetheless, it's an issue which has now come back to bite everybody all over
again. Okay? And, frankly, if back in the 1950s you could have said,
"We're going to use vaccines which have no SV40 in them," you would
have saved yourself an awful lot of trouble over the last, what, 40, 50 years
or so. Okay?
So
regulators look at this and they shudder.
Whenever you say formalin and SV40, they'll shudder at you. Okay?
The
second thing is simian cytomegalovirus ‑‑ again, this is a ‑‑
this is an issue which has cropped up from time to time where it seemed
unlikely somehow that simian cytomegalovirus was a common contaminant of
polio. It seemed unlikely that if it
was present it could possibly infect human beings. And on the other hand, when you start looking at polio vaccines,
some of them at least, you can find simian cytomegalovirus sequences present in
them, simply because of the cell cultures they are growing on primary monkey
kidney cells that they are growing on.
Okay?
And
this was something which had been going on for some time that nobody really
picked up on. Okay? But none of this is there, and it also
appears that some of these viruses, for example, will infect human diploid
cells, so they are able to infect human cells of some description or
other. And that's really quite a recent
event.
I
don't, again, think that this is a public health issue, insofar as there was no
infectivity associated with them. But
nonetheless, this is a major issue, and I guess it's a public issue as well, a
public opinion issue apart from anything else.
So
regulatory approaches are really very, very cautious when it comes to the
possible virology of what's going on here.
And when you have a complex system such as the influenza isolate
production and leading on to vaccine production, it will be examined extremely
carefully I think to make sure that nothing too bad is going to happen.
And
the conclusion, really, I have is here.
That if you have a great deal of experience at something, based on the
clinical experience, such as you had with an influenza vaccine over the last 50
years where you make your isolates on eggs and you pulse everything on eggs,
and then you make your vaccine on eggs and you inactivate it, and so on, okay,
and you know that you don't have much of a problem with that, that's a very,
very good system to actually stick with, because you know you don't have much
problem with it.
If
you start changing things a little bit, I think you've got to make sure that
you know what you're doing. So you
either do it by clinical experience or by knowing what you're doing. Okay?
That's
it. Thank you very much.
(Applause.)
CHAIRMAN
OVERTURF: We can continue the discuss
at this point, and Dr. Minor is available also for questions. Bruce.
DR.
GELLIN: Can you buy qualified VERO
cells? I mean, is there somebody who
makes this stuff and you just go out and purchase it? Or does everybody have to do their own? How does this work?
DR.
MINOR: Manufacturers have qualified
VERO cells. Okay. You can probably go to a manufacturer and
try and buy them from him. A lot of
effort goes into making them qualified.
You have to bear in mind that it's qualified when it leaves the
manufacturer's premises, and you can wreck it just like that. Right?
(Laughter.)
Right? So just because you bought it as a qualified
doesn't mean that by the time you've got it laid down as a bank in your system
that it's qualified again. Right? Okay?
Right?
CHAIRMAN
OVERTURF: Yes, Dr. Markovitz.
DR.
MARKOVITZ: I'm just curious ‑‑
this is probably naive, but is it not possible to either just buy or make
qualified cell lines, get them to all of the centers that collect samples of
influenza, and then at least hope that they don't, you know, goof them up, and
then you would have the whole chain.
I
know there's proprietary issues, but can't somebody develop ‑‑ I
mean, can't the government develop its own qualified cell line? This may be naive, but it seems too
straightforward to not at least ask.
DR.
MINOR: I think ‑‑ I think
you have to bear in mind there is a large number of labs involved in this,
right, that you really want to be sure that you know what they're all
doing. Okay? I think the example that Walter Dowdle referred to earlier of the
polio network is actually a good one, because I think there you've got a real
seriously disciplined bunch of people, actually, who are ‑‑ so in
principle it can be done I guess. Okay?
If
you think that a qualified cell line will actually last the 15 passages, which
it probably will do, maybe you could do that.
But it would require a lot of investment and effort to actually go
there, and you'd have to make sure that you actually trusted the results I
think.
DR.
ZAMBON: I'm not sure if I can switch
this on. It's on, is it? Okay.
Can everyone hear? I have a few
remarks to make, which may be relevant in the context of the discussion, partly
as running a national influenza center and partly also as being, if you like,
one of the people ‑‑ advisors on diagnostic virology strategies in
the United Kingdom.
I
think, firstly, it's important to plan for change. Diagnostic virology techniques, of which isolating influenza
viruses can't be considered in isolation, we are changing. We're in a changing world, and things we can
see already from the discussions that have been had that the amount of egg
isolation has diminished over the last decade or so. And very simply, that's a question of economics.
How
do you use your resources? You do
things which are much more efficient, so it's more efficient to work in cell
culture than it is to work in eggs.
Now,
that doesn't mean to say that you have to eliminate eggs from the vaccine
production system, but you do have to plan how you might incorporate it using
national influenza centers, which is where you get your isolates from.
And
the business of isolating a flu virus
very rarely comes in as a separate category. You're usually trying to do that alongside other things.
The
second thing to take into account when you consider your options is where do
most of the flu viruses which end up in vaccine come from? They don't come from American labs. They don't come from European labs. They don't come from the developed
world. The majority of them come from
the developing world, and the issues of resources there are much more critical
than they are in the developed world.
And
the reason I make that point is because although the example of the polio
laboratories using accredited cell lines for the isolation of polio viruses is
indeed a very good example, the polio viruses are not isolated for the purposes
of making a vaccine. They are isolated
for epidemiological work. So,
therefore, if there is a model, or if there is some problem with the way that
the cell lines are treated, it actually doesn't matter at the end of the
day.
So
my point is I think you need to be very careful about a strategy which says
we're going to put our accredited cell lines in 110 national influenza centers
and expect the quality control to be maintained in the most resource-poor
countries. I know how we would struggle
in the United Kingdom to do that, alongside a raft of other
responsibilities. And personally, I
don't think it's actually an option.
But
I do think that you have to plan for change, and you have to look at new
diagnostic techniques and how they may impact on the characterization of
influenza isolates.
Those
are remarks based on experience, really.
And I hope they contribute to the discussion.
CHAIRMAN
OVERTURF: Dr. Royal.
DR.
ROYAL: I just have a quick comment
regarding what was said about SV40 virus.
I was under the impression that actually there is evidence that
malignancies are starting to appear in sort of emerging data 40 years later to
suggest that vaccinees in fact may have been at greater risk for developing
cancers that he mentioned, as well as a few others. At least at the point we are it might warrant some additional
discussion concerning the issue.
DR.
MINOR: I don't think there's an issue
about discussion. Okay? I mean, I'm not convinced that the evidence
stacks up to say that ‑‑ that there is an increase in tumor
incidence in these ‑‑ in these particular people.
I
think the ‑‑ the issue arose because there were SV40 sequences
present in them, and the question was, well, where did they come from, are they
causal, all that kind of stuff. And the
debate continues. I mean, there is no
question that the debate continues, okay, and there is no question that it
gives a lot of people a lot of headaches.
Okay?
But
I'm ‑‑ I'm not sure that there's a causal link actually being
convincingly demonstrated there, frankly.
CHAIRMAN
OVERTURF: Dr. Monto, you had a comment?
DR.
MONTO: I just want to thank Maria
Zambon for her comments, her very practical comments, because I think we have
to view the various options in a practical way. One of the problems that we're going to have with the increasing
use of rapid diagnostics is a decrease in the number of flu isolates from
various parts of the world.
What
we want to do is to increase the number of flu isolates, so we don't have to
play the small numbers game in terms of making vaccine decisions. It is totally impractical to think that
many, if not most, national influenza centers will be able to handle certified
cell lines in a way that we can be comfortable that isolates were made
following good laboratory practices, or whatever, techniques.
And,
therefore, I think we need to focus on the other options, and I can't think of
any additional options in terms ‑‑ one of the things that ‑‑
and, frankly, I think we need to back off for a minute and remember that we are
in many ways consumers of what is going on out there in influenza surveillance.
This
is a relatively poorly funded, or has been poorly funded activity in the
past. Many of the developing countries,
where most of our strains come from, have never identified influenza as a high
priority pathogen, and, therefore, have not really put their own funds into
developing influenza surveillance, influenza identification techniques. Until this changes, we're going to have
certain generic problems, since we are consumers rather than ‑‑
rather than suppliers in this ‑‑ in this area.
CHAIRMAN
OVERTURF: Dr. Cox.
DR.
COX: I think now that I've kind of got
a flavor of some of the thoughts around the table, I'd like to just make a few
clarifying comments as well. And I'll
be echoing some of the things that have already been said.
We
were actually about a year ago tasked with reisolating SARS coronavirus in
certified cells, so that they ‑‑ this material could be made
available to people who were interested in developing SARS vaccine.
And
so we actually received some certified viral cells from one of the
manufacturers, and then invited an FDA consultant, actually an ex-FDA employee,
to go over all of the paperwork and everything that would be required in order
to make sure that what we produced at the end of the day would be acceptable in
terms of the regulatory requirements.
It's
actually extremely onerous, and I would doubt very, very much if the national
influenza centers ‑‑ very many national influenza centers at least,
not more than one or two, would be able to put systems in place so that they
could actually provide the documentation that would be necessary.
So
I think that we're really faced with a situation where some collaborating centers
or other centers that are set up to do this type of work would be responsible
for soliciting the original clinical specimens from the originators.
And
I must ‑‑ and I want to mention here that the military has for us
been an extremely excellent source of original clinical material, and we've
actually ‑‑ last year in response to what was going on with the
Fujian-like viruses, we started a very concerted effort to solicit original
clinical specimens from originators around the world and then to try to isolate
those viruses in eggs.
We
had very poor yield in eggs, so we then had to go to SPAFAS chick kidney cells
to get the original isolate, and then move on to growth in eggs. So there are ways that we can do this, but
it will require a lot of sensitivity, as Maria said, to the need to change
methods. There will be a need for
additional resources within the system to make this happen, but I think there
are some solutions available.
CHAIRMAN
OVERTURF: To me, it sounds like the
system is ‑‑ that actually the surveillance issues are very linked
to the eventual vaccine production.
Since so many of the ‑‑ obviously, I would think the
committee would want to spend a lot of time actually, first of all, enhancing
surveillance. But in order to do that,
it sounds like it's going to be linked to the issue of cell culture, since
those are going to be the cell cultures.
So
I think eventually they are going to have to come up with a system to clean up
these ‑‑ I guess I can use that term ‑‑ these cell cultures,
because that's probably what's going to be used for the primary isolation.
I
think the other issue that's going to come up is that with the ‑‑
this is a problem for laboratories worldwide in a whole lot of issues. But the continued use of rapid testing to
solidify people's diagnostic clinical impressions is also another thing that is
going to decrease the number of isolations which are necessary ultimately ‑‑
as Dr. Monto pointed out, we as consumers need those ‑‑ need those
isolates.
So,
unfortunately, I'm not sure I heard anything that was too encouraging about
cell cultures, but it does seem to me that one of the things that we really
need to do is to ‑‑ is to really, first of all, enhance
surveillance by any methods. But if
that means that we're going to have more cell culture isolates to deal with, we
also are going to have to deal with the second issue of cleaning those up.
Yes.
DR.
COX: I'm not sure that I was actually
very clear, and so I'll try once again.
We definitely do need to enhance surveillance, and we'll continue to
work with WHO to improve surveillance in countries ‑‑ in developing
countries as well as in developed countries.
And I'm hopeful that over the next few years CDC might have some
additional funds that could go into enhancing surveillance, particularly in
developing countries.
Having
said that, I'm sure that the laboratories in these developing countries will
want to use MDCK cells. But we can
still go back to them and get the original clinical material, have that shipped
to CDC, or other central laboratories, where those original clinical samples
can then be reisolated in a clean environment and clean cells or in eggs, as
appropriate for the technology that's being used.
And
I ‑‑ I really think that that's probably about as good as it gets,
because having had quite a lot of experience training people in these
countries, and seeing the resources that they have available, I think it's just
unlikely that they could ‑‑ could ‑‑ that we would be
very comfortable working with the cell culture-derived material.
CHAIRMAN
OVERTURF: Thank you, Dr. Cox. That's very useful clarification.
Yes,
Dr. Karron.
DR.
KARRON: So just to follow up, Nancy,
and make sure I understand. What you
would see as a barrier right now is actually not the quality of our
surveillance perhaps, but the availability of these qualified cell lines in WHO
‑‑ select WHO reference laboratories.
DR.
COX: I think there are gaps in
surveillance. There is no doubt about
it. There are ‑‑ there are
gaps ‑‑ for example, right now there are outbreaks of Avian H5N1 in
poultry in Laos and Cambodia, and we have no WHO collaborating national
influenza centers in these two countries.
And as far as I know, there aren't trained individuals who can isolate
influenza viruses.
So
there are gaps, and we'll continue to work with WHO to kind of plug those
gaps. But in terms of the material that
we do get, and that we are are getting, I think we can ‑‑ we've
been working to get more original clinical isolates ‑‑ specimens
from around the world. We have several
very good sources, including the military surveillance network.
And
I think we can really expand on what we've been doing in the past few years and
try to make this ‑‑ the system work. And if there are any other good ideas that come up, certainly we
can work to make it happen by incorporating others into it.
But,
yes, we need certified cell lines, and we need more isolates.
CHAIRMAN
OVERTURF: Dr. Markovitz.
DR.
MARKOVITZ: Yes. Thank you, Nancy. That's extremely helpful information. I was curious, though ‑‑ one other thing I might
address to you or others who actively work with flu in the lab. In following up on a discussion I had the
other ‑‑ yesterday with some of our industrial colleagues, the
issue arose of if you are actually going to end up growing these things in
mammalian cells.
Can
you get high enough titres? You know,
in other words, if it ‑‑ if the final process were making ‑‑
you know, you were going to use this all the way to a vaccine, can you grow it
efficiently enough in mammalian cells versus eggs? And I'm asking if you could answer that.
DR.
COX: I can only answer a very small
part of that question. We can grow the
viruses well enough to characterize them and hand them over to the
manufacturers. Whether they grow well
enough for the manufacturers to develop a viable product with ‑‑ or
not, I ‑‑ you know, that would have to be answered by the
manufacturers.
DR.
EGAN: Maybe if I could just try and
rephrase the question a little bit and the discussion. Let's assume ‑‑ you know, given
that an isolate ‑‑ a flu isolate has gone through a cell line,
mammalian cell line, MDCK or VERO, of various degrees of qualification, it may
have started out as very, very well qualified, and then may be of questionable
or unknown qualification later on.
But
given that you've got this cell isolate, this flu isolate that has gone through
these cells, and there may be some questions, there may or may not be problems,
but certainly questions and concerns, can that isolate be cleaned up, rescued
if you will, by subsequent techniques ‑‑ for example, through a
plaque purification on the cells, the qualified cells that you are going to use
for production, or through a reverse genetics?
I
think this was the issue that faced us last year. So we want to come back to that question.
And
then perhaps for Dr. Decker I'd like to ask, you know, if this were done, these
were rescued/cleaned up, would the manufacturers have any concerns, particular
concerns, about the acceptability of a seed that were produced this way?
CHAIRMAN
OVERTURF: Dr. Decker.
DR.
DECKER: I'll end up with your question,
Bill, not start with it. Just before
Dr. Egan spoke, I was going to comment on a matter that he kind of subsumed. I was going to say, given what I've heard
here, I want to go back and readdress the comment that was made earlier that
clearly option two is not satisfactory.
I don't recall who said that, and maybe I misphrased it, but that's the
sense I carried away from it.
And
I don't ‑‑ and I questioned that.
I was questioning that before Bill spoke, because it seems to me that
what we want here are as many viable options as possible. What I think I see over and over again is
that we don't know what nature will hand us.
We don't know where it will hand it, and we want all of the tools
available that will work in our toolbox.
For
that reason we ‑‑ we want reverse genetics techniques, but that
doesn't mean we throw away classic reassortant techniques. They've probably remained the most useful
most of the time.
For
production, it's wonderful to have cell culture technologies. I don't think anybody thinks we're going to
throw away eggs, because each will have its appropriate purpose.
And,
similarly, here it may be that the single best technique may not be growing it
in unqualified cell lines and then rescuing them through plaque
purification. But knowing that we can
do that, if that's what actually happens some day, it might be enormously valuable.
So
I would ‑‑ I would not at all turn my back on option two. Even if it's not the way we hope things play
out, it may be the way things actually do play out. And so I think that would be very valuable.
Coming
to Dr. Egan's question, he ought to know when he asks a question like that I'm
going to turn it right back at him. I
cannot contemplate, as a manufacturer, having FDA hand us a strain and say,
"We hope it's safe."
(Laughter.)
DR.
EGAN: We certainly appreciate that vote
of confidence.
(Laughter.)
CHAIRMAN
OVERTURF: Further questions? Discussion?
Yes, Dr. McInnes.
DR.
McINNES: Thank you. The reason I was staggering over all the
bags back here to get to the table was to try to make a comment, exactly what
Dr. Decker did far more eloquently.
I
think what I was hearing before was sort of this all or none. It had to either go all the way or another
way. And I think the balance was the
system that we have is working extremely well, but it doesn't always work. And so I think what FDA was trying to lay
out for us were some options for strategies when that optimum isn't working.
We
saw the value of it in ‑‑ with the SARS experience. We're going to see the value of it in the
pandemic experience. And last year in
the interpandemic, an approach was in fact ‑‑ could be possible to
have solved some of the dilemma that we were faced with last year.
So
I would plead not to throw out what technology will offer us in these very
difficult circumstances when there may be no other option.
CHAIRMAN
OVERTURF: Yes. Dr. Minor.
DR.
MINOR: My difficulty with option two
is, how do you know that it has worked, right?
I mean, how do you know that you got ‑‑ you got rid of
whatever stuff you had in there in the first place, if you had stuff in there
in the first place.
I
think if you go through reverse genetics, I think you can be reasonably certain
that you've cleaned it up. Right? If you do the egg thing, I think you don't
care whether you've cleaned it up. but
in the case of option two, how do you know that you've actually done what you
meant to do, right?
CHAIRMAN
OVERTURF: Yes, Dr. Decker.
DR.
DECKER: True. Noted. But at the same
time, let's look at another option, which would be let us suppose that there
were ‑‑ we had a wonderful supply of a qualified cell line with no
IP barriers, there was widespread distribution to every lab that wanted
it. As has been pointed out, the day it
leaves the door it's not qualified anymore.
And
to the extent that you think that you're following that approach, aren't you
really in option two? And hadn't you
better have developed, to the extent you can, your techniques for subsequent
purification?
If
you go the reverse genetics road, or you work in eggs, you may sidestep
that. But we saw last year, we could
have wished all we wanted that they had worked in eggs last year, but the
Fujian isolates were in unqualified cell lines, not in eggs.
And
had we had in our hands at that time a ‑‑ a procedure that we had
some faith in for ‑‑ I'll call it plaque neutralization, but it
could be some entirely different technology, but some way of taking that next
step in a known timeframe, had this committee known a year ago in two weeks
we'll have an isolate that can be used for manufacture, I think we would have
behaved very differently than we did.
And
so I'm all for our developing broader techniques here, even though no one
technique may be perfect.
CHAIRMAN
OVERTURF: Yes. I think I would agree. I think at this point it seems too early in
this whole issue to throw out all ‑‑ any option, really, until they
have been more fully explored. And I
also think there may be a certain urgency in certain situations.
A
true pandemic of a very lethal influenza might incite a different level of
caution than ‑‑ and also might ‑‑ might be backed by
certain guarantees from manufacturers, and so forth, against liability,
etcetera, that would not occur, for instance, in the annual routine
immunization procedures.
So
I think it's probably too early to throw out all ‑‑ all options at
this point.
CHAIRMAN
OVERTURF: Dr. Gellin, you had a ‑‑
DR.
McINNES: Just to address the
comment. I think there's a ‑‑
there may be a range of qualification on the cell lines that are under
consideration, all the way from fully qualified cell line that is in the hands
of the manufacturer to perhaps a ‑‑ such a cell line that has been
transitioned to a very competent and capable lab, and, in fact, maybe the full
requalification process hasn't gone, all the way to mashed up dog kidney cells
sitting somewhere out there.
And,
I mean, this is a full range. And so
perhaps what that has to be tied to is, in fact, in such circumstances there
would be a balance of data to support, in fact, almost a relief on ‑‑
and characterization of the reference virus, which I know right now is not done
in interpandemic times. So I think
it's, again, a balance of data that might need to be put forward for
consideration as a reference virus.
CHAIRMAN
OVERTURF: Dr. Karron.
DR.
KARRON: I guess the one other comment
I'd like to make, and my only concern about what Michael said, is that I do
think it would be useful to have a hierarchy of preferences, because I do think
that it may influence how you move forward.
If
you ‑‑ if you say that any of these options are fine, and they may
be, or there may be situations where we want to be able to exercise all of
them, it doesn't perhaps push us to see if we can get qualified cell lines into
the hands of, you know, WHO reference laboratories, or certain other
activities.
So
I think it might be useful at least to say we will consider all of these
options, but these ‑‑ this is the order in which we would like to
be able to have isolates.
CHAIRMAN
OVERTURF: Dr. Myers.
DR.
MYERS: I think there ‑‑
we're talking about a couple of apples and oranges issues. I think when we talk about pandemics and we
talk about SARS and we talk about emergency circumstances, we may be talking
about a different set of circumstances.
But
what, Mike, you're talking about is a routine year-in and year-out isolation of
seed viruses for ‑‑ and the issue we were talking about last
year. I think the issue of perception
of vaccine safety ‑‑ we are obligated in the routine set of
circumstances to have the safest potential seed viruses that are available to
us.
And
although I understand what Nancy is saying about current good laboratory
practices not being currently a common ‑‑ commonly used in
diagnostic laboratories or in many of the laboratories around the world where
these isolates are obtained, I think strategies of trying to bring the clinical
specimen to a CGLP setting with documented cells is a strategy that is worth
developing to increase repertoire on a year-in and year-out basis.
And
I think that should be a priority, a lot higher priority than trying to clean
up undocumented, unqualified, potentially contaminated cells.
CHAIRMAN
OVERTURF: And I think, actually, the
strategy that Dr. Cox had suggested, which was to link this to your
surveillance program, so that you go back to the original isolates, and ‑‑
and use appropriate techniques to isolate the initial seed viruses, is probably
going to be in the short term a very good answer.
But
I ‑‑ I also would say that probably there is going to have to be a
priority for some of these other techniques for pandemic situations and other
kinds of isolates. I would agree that
for the routine yearly isolation of viruses, and production of vaccine, I think
we have an obligation to make the safest seed lots.
I'm
sure ‑‑ and I'm sure the manufacturers are not going to be happy if
we give them anything that's ‑‑ anything less than absolutely pure
and good.
DR.
HJORTH: Yes. I was interested in Nancy's comment about the SPAFAS chick kidney
cells. And I think that might be
another option. These ‑‑
these might not ‑‑ these might be a little easier to deal with than
certified cell lines, and I was wondering ‑‑ Nancy mentioned the
isolation rate was higher.
I
just wonder, is it substantially higher, so that it would really be worthwhile
considering these instead of eggs? But
perhaps isolates from these cells might be considered as though they were egg
isolates.
DR.
COX: They are considered as egg
isolates now. And they do give a
substantially higher isolation rate for the current H3N2 viruses than eggs do. So ‑‑ so if we take the original
clinical specimens and put them into eggs and SPAFAS chick kidney cells, we're
more likely to get an isolate out of the SPAFAS chick kidney cells, which can
subsequently be passaged in eggs.
So,
but they are not ‑‑ I mean, they are a little bit finicky and
fiddly, so you have to kind of know what you're doing. And it works best if you've got them going
on a routine basis, and you've got somebody who is accustomed to looking at
them week after week. And they are
actually more difficult to deal with than the MDCK cells that are used in most
of the reference labs.
CHAIRMAN
OVERTURF: Yes, sir.
DR.
EGAN: Yes. Dr. Overturf, I certainly appreciate your comment, but would like
to ask you to maybe clarify it a little bit more, maybe other people that are
here. Do you consider an isolate that
had gone through, for example, an MDCK cell or a VERO cell, and then
subsequently go through a reverse genetics procedure or go through several
rounds of plaque purification to be any less safe?
You
know, and, if so, you know, what ‑‑ you know, what ‑‑
what do you see as the safety concerns?
Maybe to have a little more discussion of this.
CHAIRMAN
OVERTURF: Well, and I ‑‑
some of us here are not experts in this area.
But I ‑‑ I think it has been pretty clearly laid out that
they cannot be at the present time considered as safe as those that have been
primarily isolated in eggs, although I think we've taken a lot for granted
about eggs for years, so I'm not sure that we have all that we really need to
make that decision.
Yes.
DR.
MONTO: I would feel quite comfortable
with the reverse genetics procedure, given certain caveats in terms of what you
got out being what you put in. And we
can do that in terms of sequence ‑‑ sequences, etcetera.
I
think that would be ‑‑ if you follow Dr. Karron's suggestion and
come up with a hierarchy, that would be my ‑‑ my preference in
terms of developing. And I think we
need to develop protocols to ‑‑ to be able to handle these
different options.
I
think the option two is an attractive option, but there I think there would be
many questions, certainly relative to what Dr. Minor said, in terms of how do
you prove that it's ‑‑ that nothing adventitious has gotten in
there? How many plaque purifications
would you require? Would there be
additional safety testing required, especially ‑‑ do you still see
that the egg ‑‑ going back to the egg ‑‑ is going to
filter out any human or primate viruses that could have gotten into the
mix?
So
it would be useful to see more detailed protocols developed for some of these ‑‑
some of these options.
CHAIRMAN
OVERTURF: Dr. LaRussa.
DR.
LaRUSSA: Is there a sense that in the
coming months there is going to be more detailed information available, so that
the committee could actually evaluate the different rescue options and make
recommendations? Or is it just really
too early?
DR.
EGAN: It's probably a bit early for
that. But, you know, this is an issue
that certainly arose last year, and we'd like to have a fuller discussion of
it. And that's why we're bringing the ‑‑
you know, the question back to this committee.
And, you know, maybe some of the virologists here can, you know, give
some additional comments.
CHAIRMAN
OVERTURF: Dr. Karron.
DR.
KARRON: I would just say that there's
probably ‑‑ to follow up on what Dr. Overturf said ‑‑
there's probably diversity of opinion among the committee members about whether
a virus that, say, under scheme two had been isolated and was then either
recovered by reverse genetics or plaque purified and put through eggs ‑‑
you know, how safe that would be.
And
I'm not ‑‑ I'm not sure that there's a unanimity of opinion and
that that would be less safe. I think ‑‑
my guess is that there's probably a diversity of opinion on that issue.
CHAIRMAN
OVERTURF: I think the diversity is
partially based upon an awful lot of suppositions and guessing that we really
can't substantiate in any way, shape, or form.
So I'm thinking there's a lot of uncertainty.
I
think one of the things that favors the current methodologies is a long record
of ‑‑ of, we think, safety.
But even there there are some ‑‑ there are some ‑‑
some loopholes. But I think unless you
have strong evidence to deviate from that in safety and other systems, that's
probably ‑‑ probably ‑‑ I think most of us probably
would be uncomfortable with that.
I
think I also would agree that the reverse genetics approach probably has the
best assurances ultimately for proceeding.
But I think we're ‑‑ we're not there yet at this point. I don't know how others feel.
DR.
DECKER: I would agree with that.
CHAIRMAN
OVERTURF: Dr. Decker.
DR.
DECKER: Yes, just I agree. And following up on Dr. Karron's comment, I
mean, I think that was helpful, and I think it's been implicit, but I'll make
it explicit. A, isolation remains ‑‑
if we had our choice, that's the way we'd prefer to see it come.
And
if it can't come that way, I would say that the reverse genetics is probably
second choice, because in my mind having an allegedly certified cell line out
of somebody else's hands for some period of time really drops us right into
option two. So that those two go
together with me.
If
you're going to go with that certified cell line in a non-central, non-FDA
level, CDC-level lab, or something else, then you're already in option
two. So those merge together for me to
become the third choice.
CHAIRMAN
OVERTURF: Dr. Karron.
DR.
KARRON: Maybe Nancy can comment on
this. A non-FDA, non-CDC level
laboratory ‑‑ I'm not familiar enough with the WHO influenza
laboratories to know if they are ‑‑ this may be a loaded question ‑‑
but comparable to yours in terms of abilities to, for example, handle a
qualified cell line, maintain it, do the kind of quality assurance that's
necessary.
DR.
COX: I would have to say that the
majority of the national influenza centers would not have the resources to do
this. You need to have a separate room
which you can devote for a specific period of time. It has to be completely cleaned up.
You
have to have the cell ‑‑ the certified cells locked and in a, you
know, very clearly delineated area of the freezer. You have to have very extensive documentation of all of the media
components, and so on and so forth, just to meet GLP requirements. And so for ‑‑ I doubt that most
would have the resources, really, to devote to this kind of an activity.
DR.
KARRON: Right. I was actually speaking about the WHO
collaborating centers. I was
differentiating ‑‑
DR.
COX: Oh, the collaborating centers.
DR.
KARRON: ‑‑ between ‑‑
between option one and option three in the ‑‑ in the range that we
were given.
DR.
COX: There are four WHO collaborating
centers, and I would have to speak with each of the directors individually to
find out if they would have those resources.
CHAIRMAN
OVERTURF: Dr. Markovitz.
DR.
MARKOVITZ: Yes. It seems like what Nancy said a while ago
seems to be when we're looking for other options other than standard options, I
mean, the idea of, you know, getting the original clinical isolate to a lab
such as yourself ‑‑ yours or perhaps a comparable lab here, that
seems to make infinite good sense as an alternative.
And
I'm a bit perplexed. In spite of being
a molecular geneticist for about 80 percent of my professional life, I'm not
quite sure where we actually stand on these reverse genetics in practical use
right now with flu, you know, for vaccine.
I mean, it looks ‑‑ I mean, I've heard the term bandied
about, but I'm not completely sure where we stand.
Could
somebody clarify that for me in five easy sentences?
CHAIRMAN
OVERTURF: We'll give you six sentences,
Dr. Minor. Could you do that in six?
(Laughter.)
DR.
MINOR: Okay. I mean, this is purely in technical terms, okay, so it's not in
terms of the practicalities of it. Once
you've actually got the strain out, what can you do with it, and all that kind
of stuff, it's purely technical. Okay?
What
you do is you'll extract the nucleic acid, you'll clone it into a plasmid, and
then you'll recover your virus from the plasmids that you've cloned. Okay?
To
my mind, everything that happens before you actually extract your nucleic acid
from your virus is, therefore, cleared out of the way completely, right? Okay.
It's completely irrelevant, okay?
Anything
that happens after that is your own fault, okay? So if you're ‑‑ okay? So if you're doing things under GNP, or whatever, okay, then I
think from that point on you're in the clear.
This is why I say I think that if you can it by reverse genetics, I
think then you really are clean in terms of you don't really necessarily care
where your isolate came from, because you got rid of everything that might have
been there in the first place.
DR.
MARKOVITZ: Yes, I completely agree with
that.
DR.
MINOR: Right.
DR.
MARKOVITZ: From a virological point of
view and molecular. But what I'm
curious is ‑‑ the way these isolates are actually arriving at the
doorstep prior to being perhaps becoming a vaccine isolate, they're not coming
through reverse genetics right now, right?
I mean, they're just coming ‑‑ they're growing in cells,
right?
DR.
MINOR: That's right. Well, I mean, our Vietnam/11/94 thing ‑‑
I mean, this came as an egg isolate from somewhere. I mean, I ‑‑ Hong Kong apparently. Hong Kong?
That's okay. So, but I ‑‑
my point is that I don't care where it comes from, if I've gone through reverse
genetics. It doesn't even have to come
as a virus. I mean, it could come as a ‑‑
it could come as a PCR fragment, provided it's the right PCR fragment. Okay?
Provided you can clone it and you can clean it up.
DR.
MARKOVITZ: But in terms of what we're
doing right now, how big of a percentage of the effort towards a vaccine in a
given year is coming from reverse ‑‑ you know, virus derived from
reverse genetics? That's what I'm ‑‑
DR.
MINOR: Oh, zero. Zero.
Zero.
DR.
MARKOVITZ: Yes, okay. So that's my impression, but yet I keep
hearing reverse genetics, and I ‑‑
DR.
MINOR: It's just a good idea, you know?
(Laughter.)
DR.
MARKOVITZ: Yes. So, obviously, it's the best idea if it can
be up and running. But how close are we
to having it up and running in this setting that would impact on the ‑‑
the committee issues, which is year-to-year vaccinology. That's my real question.
DR.
COX: There are laboratories that have
already produced vaccine candidates for age five, as you heard yesterday. There are intellectual property issues
related to this technology, however, that would have to be worked out.
CHAIRMAN
OVERTURF: Dr. McInnes.
DR.
McINNES: I mean, I think we shouldn't
forget there is a product licensed in the United States that starts its origin,
its reference virus origin, through reverse genetics. So, I mean, I think the answer that there isn't any, we ‑‑
yes, there is.
DR.
COX: Could you clarify?
DR.
McINNES: If we're talking about the
live attenuated cold-adapted influenza vaccine, what are you saying?
DR.
COX: That's classical reassortment, I
think, yes.
DR.
McINNES: Correct. But, I mean, the concept of using reverse
genetics to develop influenza vaccines is not new. I thought that was what you were saying.
DR.
COX: No. We were just ‑‑
DR.
McINNES: Perhaps I don't understand
you.
DR.
COX: Yes. We were just saying that there's no license ‑‑
there's no product that's currently used that's derived by reverse genetics.
DR.
McINNES: Okay. I'm sorry.
I misunderstood you.
CHAIRMAN
OVERTURF: Dr. Egan, I think ‑‑
I think you heard a priority here, and I think the feeling of the committee is,
as stated by Dr. Karron, probably diverse.
But I do think that there is a sense that there is a priority with the
first priority really being for reverse genetics.
And
then I don't think people are comfortable yet with rescue methods for
recovering virus from unqualified cell lines.
Did you ‑‑
DR.
EGAN: Although there was some comfort I
guess through reverse genetics. But ‑‑
CHAIRMAN
OVERTURF: Yes.
DR.
EGAN: But maybe a little bit less so
with several rounds of plaque purification.
CHAIRMAN
OVERTURF: Yes.
DR.
MARKOVITZ: That sounds right to me,
yes.
DR.
EGAN: Okay. This has been, you know, very helpful for us. And I think we can certainly take this
discussion and the comments that all of the committee members have made and
probably ‑‑ and try and put something together, a little more of a
directed package for future comment and discussion, both here and with other
regulatory agencies.
Thank
you.
CHAIRMAN
OVERTURF: Was there any further
discussion? We actually are about 45
minutes ahead of schedule, mostly because we had no speakers at our open
session. So I don't believe there's any
other business.
DR.
FREAS: No. I would just like to thank the committee members for their
discussion, comments, recommendations.
We really appreciate it.
Dr.
Overturf, you did an excellent job as Chair.
I'd like to thank you.
The
guest speakers who came from overseas and long distances, we really appreciate
it.
And
I would like to give special thanks to my friends at CDC. Dr. Cox, we couldn't have done this meeting
without you and your colleagues.
And,
Dr. Levandowski, I know you had many late hours and many late nights.
We
appreciate everybody's input. Thank
you.
(Applause.)
It's
adjourned.
(Whereupon, at 12:23
p.m., the meeting was adjourned.)